What does HackerNews think of browservice?
Browservice: Browse the modern web on historical browsers
It works in virtually all "old" browsers and can be very useful for older computers.
https://github.com/ttalvitie/browservice
For very old web browsers, WRP works similarly but replaces the javascript with an imagemap.
Also rdp/freenx/x2go/vnc can help.
That doesn't make the old computer a full independent desktop but it can avoid sending a perfectly good keyboard/trackpad/monitor in the landfill. And unless you are a dev, 99% of the time you need a browser you already have network and won't point to localhost so that remote faster box can be connecred through vpn anywhere.
There's also Browservice: https://github.com/ttalvitie/browservice
(which I discovered via Michael MJD's YouTube channel: https://www.youtube.com/watch?v=5MjZdKtv9ak)
Can't remember the name, though (and it's also hard to search for).
edit: browser history to the rescue, it's https://github.com/ttalvitie/browservice