WordPress Custom Development Issues (WordPress Codex/PHP/JavaScript/AJAX)

I have a list of issues that need to be fixed on my website. These can be easily fixed within a day with a skilled full-stack developer. As a developer myself, I am looking for someone who can provide guidance on the issues not to hand over the staging site.

I reduced the list from 17 to 8 and with in-depth details.
The theme is WP Bootstrap Starter
Here is the staging site: http://35.161.164.191


Convert Mega Menu into plain JavaScript
http://35.161.164.191/wp-content/themes/leadstart/header.php
Main JS file: http://35.161.164.191/wp-content/themes/leadstart/inc/assets/js/theme-script.min.js
or replace Bootstrap nav walker with this and have it work with Bootstrap 5.0 -
https://github.com/wp-bootstrap/WP-Bootstrap-MegaMenu-Navwalker


Fix the Search Filter
There should be no need to click APPLY to trigger the search and code needs to be converted to vanilla/plain js as well instead of jQuery AJAX. I need also a better or proper way to replace initial search results if possible.
https://prnt.sc/gxrJE9_GocOl
Example search - https://35.161.164.191/?post_type=any&s=01
The original instructions used to add filters are here - https://rudrastyh.com/wordpress/ajax-post-filters.html
My code: http://35.161.164.191/wp-content/themes/leadstart/search.php
http://35.161.164.191/wp-content/themes/leadstart/inc/loop-functions/loop-searchfilter.php
http://35.161.164.191/wp-content/themes/leadstart/inc/assets/js/archive/archive-search.js


WooCommerce 'My Account' custom pagination (must be logged in)
Numbered pagination needs to be added to custom My liked posts and Bookmarks tabs
http://prnt.sc/n13Nv49CwMfv
http://35.161.164.191/my-account/
http://35.161.164.191/my-account/my-likes
http://35.161.164.191/my-account/bookmarks
My code: http://35.161.164.191/wp-content/themes/leadstart/woocommerce/myaccount/likes.php
http://35.161.164.191/wp-content/themes/leadstart/woocommerce/myaccount/bookmarks.php


Snippets Post Type Archive thumbnail generation
Programatically set screenshot taken by WordPress Mshot as the post's featured image
https://www.wpbeginner.com/plugins/an-automated-way-of-taking-website-screenshot-in-wordpress/
My code: http://35.161.164.191/wp-content/themes/leadstart/template-parts/content-archive.php


Font Post Type Single Page
Variants dropdown and font-weight are not working
http://35.161.164.191/fonts/fv-almelo-4/
https://github.com/underscoretype/fontsampler-js
Example: https://underscoretype.github.io/fontsampler-js/
My code: http://35.161.164.191/wp-content/themes/leadstart/inc/assets/js/custom-fonts.js


Font Post Type Single Page
We need to adjust font color based on background
https://35.161.164.191/fonts/fv-almelo-4/#livemodal
http://briangonzalez.github.io/jquery.adaptive-backgrounds.js
https://github.com/briangonzalez/jquery.adaptive-backgrounds.js
My code: http://35.161.164.191/wp-content/themes/leadstart/inc/assets/js/custom-fonts.js


Consultation Page
JavaScript is not working properly, it is not showing any validation on next, and clicking on next nothing happens also if we can switch to plan js
https://prnt.sc/bFw2-68cgLtO
https://35.161.164.191/consultation
My code: http://35.161.164.191/wp-content/themes/leadstart/inc/assets/js/theme-script.min.js


Facebook Login integration (WordPress Social Plugin)
https://prnt.sc/UkWcMjQAnx0u
This is the error I get when trying to login with Facebook:

Cannot Load URL
Error - the domain of this URL isn't included in the app's domains. To be able to load this URL, add all domains and subdomains of your app to the App Domains field in your app settings.

Link to the plugin - http://35.161.164.191/wp-admin/options-general.php?page=wordpress-social-login
Link to my Facebook app - https://developers.facebook.com/apps/528820465477599/settings/basic/?business_id=573632677020865