I really appreciate what you wrote in that post re: dropping support for pre-Windows 10 operating systems.

I'd like to snag that latest previous version which still has compatibility with older OS's, anyone have a reliable link handy?

(I couldn't quickly find a "Previous Versions" list on their website)

It looks like all the old files are still hosted on the server. You can just replace the version number in the download links with one of the tags from https://git.zx2c4.com/wireguard-windows.