Power BI Left Side Filter Pane -- install a UserScripts browser extension (like TamperMonkey, GreaseMonkey, ViolentMonkey, etc) then import this file.

Power BI - Left Filter Pane.user.js

// ==UserScript==
// @name         Power BI - Left Filter Pane
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  Move Power BI report filter pane from right side of canvas to left side
// @author       James D. Bartlett III (@JamesDBartlett3)
// @match        https://app.powerbi.com/*
// @icon         https://www.google.com/s2/favicons?domain=powerbi.com
// @grant        none
// ==/UserScript==

(function() {
    // define checkExist function with interval set to run every 500ms
    let checkExist = setInterval(function() {
        // set filterPane variable to result of document query for first element with TagName "outspace-pane"
        let filterPane = document.getElementsByTagName("outspace-pane")[0]
        // if filterPane is undefined...
        if (filterPane == undefined) {
            // console.log("Filter pane not found. Waiting 500ms...") // notify via console log
            // continue to next iteration of loop
        }
        // otherwise, if filterPane is not undefined...
        else {
            // set canvas variable to the parent node of filterPane
            let canvas = filterPane.parentNode
            // if filterPane is not the first child of its parent...
            if(canvas.firstChild != filterPane) {
                // console.log("Filter pane found. Moving to left side of page.") // notify via console log
                // make filterPane the first child of its parent
                canvas.insertBefore(filterPane, canvas.firstChild)
            }
        }
    }, 500)
    // define rotateChevronIcon function with interval set to run every 100ms
    let rotateChevronIcon = setInterval(function() {
        // declare collapsedPane and expandedPane variables to results of document query for their respective classes
        let collapsedPane = document.querySelector('.outspacePaneCollapsed')
        let expandedPane = document.querySelector('.outspacePaneExpanded')
        // if the pane is expanded...
        if(expandedPane) {
            // set rotation of the chevron icon to 90 degrees
            expandedPane.querySelector('.collapseIcon').setAttribute("style", "transform: rotate(90deg)")
        }
        // if the pane is collapsed...
        if(collapsedPane) {
            // set rotation of the chevron icon to 270 degrees
            collapsedPane.querySelector('.collapseIcon').setAttribute("style", "transform: rotate(270deg)")
        }
    }, 100)
})();