Hey there, I took it upon myself to update the Classic Widgets plugin made by the WordPress Team and give it a brand-new refreshed feel! I have added a Settings page so you can now toggle between Gutenberg Blocks and Classic Widgets without deactivating / activating the plugin itself! I have also added the option to Sticky the Active Widgets in the Appearance subsection, so they scroll with the page, and you no longer have to scroll back to the top just to edit them.
For now, since I only added the option to sticky the active widgets back and made sure it’s compatible with new PHP versions, it uses the same data as the original Classic Widgets so when you upload the file it will act as an UPDATE instead of a whole new plugin.
It’s been submitted to WordPress itself, if they wish to accept the update.