what you are looking for is abandoning the Android OS on them and flashing something akin to postmarketOS. This can still come with a workable touch-based GUI. But also just installing things like web-servers and php runtimes via a package-manager. Surprisingly broad support: https://wiki.postmarketos.org/wiki/Devices
Exactly what I was thinking: I don't see the point of running a server on an old Android device. Just install Linux there, right? And typically there pmOS seems like a promising project!
