Run this script from console in your browser. Run this script on the page "https://miro.com/app/dashboard/"

export_all_boards_miro.js

function getBoardId(src) {
    return src.match(/boards\/([^\/]*)/)[1];
}
   
function waitForElementToDisplay(selector, itemelem, callback, checkFrequencyInMs, timeoutInMs) {
    var startTimeInMs = Date.now();
    (function loopSearch() {
        let btn = document.querySelectorAll(selector)[itemelem || 0];
        if (btn != null) {
            callback(btn);
            return;
        }
        else {
            setTimeout(function () {
            if (timeoutInMs && Date.now() - startTimeInMs > timeoutInMs)
                return;
            loopSearch();
            }, checkFrequencyInMs);
        }
    })();
}
   
function clickButton({ selector, itemelem, timewaitafter, callback }) {
    waitForElementToDisplay(selector, itemelem, (btn)=> {
        btn.click();
        setTimeout(callback, timewaitafter || 500);
    }, 1000, 9000);
}
   
   
function clickButtonMenu({ selector, itemelem, timewaitafter, callback, doCancel }) {
    let btn = document.querySelectorAll(selector)[itemelem || 0];
   
    if (btn==null) {
        console.log('undefined by selector:', selector, itemelem || 0);
        if (doCancel) doCancel();
    }
   
    if (btn.className.indexOf('exportItem_disabled') != -1) {
        console.log('do cancel click on:', selector);
        if (doCancel) doCancel();
    }
   
    btn.click();
    setTimeout(callback, timewaitafter || 500);
}
   
function whileRtbLoader(callback) {
    if (rtbLoader.rtbLoaderElement.style.display == 'block') {
        setTimeout(()=>whileRtbLoader(callback), 500);
        return;
    }
   
    if (document.querySelectorAll('.board-ui-skeleton__panel').length != 0) {
        setTimeout(()=>whileRtbLoader(callback), 200);
        return;
    }
       
    setTimeout(callback, 500);
}

function download(content, fileName, contentType, callback) {
    var a = document.createElement("a");
    var file = new Blob([content], {type: contentType});
    a.href = URL.createObjectURL(file);
    a.download = fileName;
    a.click();
    if (!!callback) callback();
}
    
    
// open all boards
let btn = document.querySelectorAll('[aria-label="Show all boards"]')[0];
btn.click();
    
setTimeout(()=> {
    var lsBoards = JSON.parse(window.localStorage.getItem('export_boards'));
  
    if (lsBoards == null || lsBoards.length == 0) {
        let boardsid = [];
        let buttonImg = document.querySelectorAll('[data-testid="board_image_original_autotest_id"]');
        buttonImg.forEach(b => boardsid.push(getBoardId(b.src)));
        window.localStorage.setItem('export_boards', JSON.stringify(boardsid));
    }
    
    load();
    
    function load() {
        var boardsid = JSON.parse(window.localStorage.getItem('export_boards'));
        // run
        clickOpenAllBoards();
    
        function clickOpenAllBoards() {
            clickButton({
                selector: '[aria-label="Show all boards"]',
                itemelem: 0,
                timewaitafter: 400,
                callback: clickBoardIcon
            })
        }
    
        function clickBoardIcon() {
            let boardId = boardsid.pop();
    
            window.localStorage.setItem('export_boards', JSON.stringify(boardsid));
            //дашборды закончились
            if (boardId == null)
                return;
    
            console.log(boardsid);
   
            clickButton({
                selector: `[src^="https://miro.com/api/v1/boards/${boardId}"]`,
                itemelem: 0,
                timewaitafter: 200,
                callback: () => {
                    rtbLoader.rtbLoaderElement.style.display == 'block';
                     openExportMenu(clickExportBackup);
                }
            })
        }

        function openExportMenu(clickBtnExport) {
            whileRtbLoader(()=> {
                clickButton({
                    selector: '[data-testid="board-header__export-icon"]',
                    itemelem: 0,
                    timewaitafter: 500,
                    callback: clickBtnExport
                });
            });
        }
   
        function clickExportBackup() {
            clickButtonMenu({
                selector: '[data-testid="board-header__export-icon--BOARD_EXPORT_BACKUP"]',
                itemelem: 0,
                timewaitafter: 20000,
                callback: backupBoardObjects,
                doCancel: backupBoardObjects
            });
        }

        function backupBoardObjects() {
            window.miro.board.info.get().then(boardinfo=>{ 
                const filename = boardinfo.title + '_' + boardinfo.updatedAt.replace(/\..*$/,'');

                window.miro.board.getAllObjects().then(elems => {
                    const jsonData = JSON.stringify(elems, null, ' ');
                    download(jsonData, filename + '.canvas.json', 'text/plain', ()=>openExportMenu(clickExportPDF));
                }).catch((err) => {
                   openExportMenu(clickExportPDF);
                });
            });
        }

        function clickExportPDF () {
            window.miro.board.getAllObjects().then(elems => {
                // chack have frame
                if (elems.findIndex((k) => k.type == 'FRAME') == -1) {
                    backToPageAllDashboard();
                    return;
                }
 
                clickButtonMenu({
                    selector: '[data-testid="board-header__export-icon--BOARD_EXPORT_PDF"]',
                    itemelem: 0,
                    timewaitafter: 500,
                    callback: clickQualityBest,
                    doCancel: backToPageAllDashboard
                });
            });
 
            function clickQualityBest () {
                clickButton({
                    selector: '[hm-tap="modal.setQuality(+quality)"] label',
                    itemelem: 1,
                    timewaitafter: 300,
                    callback: clickDownloadPDF
                });
            }
        
            function clickDownloadPDF () {
                clickButton({
                    selector: 'button[hm-tap="modal.download()"]',
                    itemelem: 0,
                    timewaitafter: 20000, //wait 20 sec
                    callback: backToPageAllDashboard
                });
            }
        }
    
        function backToPageAllDashboard() {
            window.history.back();
            setTimeout(()=> {
                load();
            }, 10000);
        }
    }
    
}, 200);