Google Chrome's date picker is pretty decent. This gives it the desired UX for copying and pasting in d/m/Y format.

NativeDateCopyPaste.js

// Google Chrome's date picker is pretty decent. This gives it the desired UX for copying and pasting.
export default function (Vue, options) {
    Vue.mixin({
        updated() {
            Array.from(document.querySelectorAll('input')).filter(input => input.type === 'date').forEach(input => {
                input.addEventListener('blur', onBlur);
                input.addEventListener('copy', onCopy);
                input.addEventListener('paste', onPaste);
            });
        }
    });

    // It should format short years when tabbing away.
    const onBlur = event => {
        if (event.target.value) setDateValue(event.target.value, event.target);
    };

    // We want to copy in the d/m/Y format.
    const onCopy = event => {
        event.preventDefault();
        if (event.clipboardData) event.clipboardData.setData('text/plain', event.target.value.split('-').reverse().join('/'));
        else navigator.clipboard.writeText(document.activeElement.value.split('-').reverse().join('/'));
    };

    // Paste should handle different formats and short days, months, and years.
    const onPaste = async event => {
        event.preventDefault();

        let value = event.clipboardData
            ? event.clipboardData.getData('text/plain')
            : await navigator.clipboard.readText();

        setDateValue(value, event.target);
    };

    // This is the date setting logic used for blur and paste.
    const setDateValue = (value, element) => {
        let day, month, year;
        if (value.includes('-')) {
            [year, month, day] = value.split('-');
            if (! year) return;
        } else if (value.includes('/')) {
            [day, month, year] = value.split('/');
            if (! day) return;
        }

        const shortYear1900sOr2000s = (new Date).getFullYear() - 1900 - 65;
        if (year && year < shortYear1900sOr2000s) year = parseInt(year) + 2000;
        if (year && year >= shortYear1900sOr2000s && year <= 100) year = parseInt(year) + 1900;

        if (! day) day = (new Date).getDate();
        if (! month) month = (new Date).getMonth() + 1;
        if (! year) year = (new Date).getFullYear();

        day = parseInt(day);
        month = parseInt(month);
        if (day < 10) day = `0${day}`;
        if (month < 10) month = `0${month}`;

        element.value = [year, month, day].join('-');
    };

    // Copy appears to not be reliable for date inputs, this will ensure the copy or paste happens.
    let cmd = false;
    document.addEventListener('keyup', event => cmd = false);
    document.addEventListener('keydown', event => {
        if (event.code === 'MetaLeft') cmd = true;
        else if (event.code === 'MetaRight') cmd = true;
        else if (event.code === 'ControlLeft') cmd = true;
        else if (event.code === 'ControlRight') cmd = true;
        else if (cmd === true && document.activeElement.type === 'date') {
            if (event.code === 'KeyC') document.activeElement.dispatchEvent(new Event('copy'));
            if (event.code === 'KeyV') document.activeElement.dispatchEvent(new Event('paste'));
        };
    });
}