Maybe sandbox it. Put it in a chroot or VM or something. It doesn't always work as there are sometimes exploits to break out of those, but worth a shot.

Also, if you're just webbrowsing, you could buy a cheapo outdated notebook/PC and slap it on there. I got old hardware even for free a few times. You can still use it for simple things, like webbrowsing or retro games.