There are no “real” alternative OS available for apple devices. You can get some IDE “lite” apps like Visual Code, Python Editor, etc. but these a meant as companions to a PC IDE not meant for compiling, linking, testing, etc. You might be able to trade the old iPad for an old laptop you can put a flavor of Linux on.

I run a Unifi USG-1 router/gateway now but before that I got a used AC1000 router from the thrift store for $5 and loaded OpenWRT on that. I eventually got an Aris modem to replace the Comcrap Gateway because it was messing with the DNS traffic, even when piHole was set as DNS for every machine. So if I were you I would go look at the OpenWRT list of units that will accept their firmware. Pay attention to the hardware revision as well as the model number, it matters.

https://openwrt.org/toh/views/toh_fwdownload

Then head over to a local thrift store or two and see if you can find any for cheep.

Eject the warp core!

Nice try, scammer.

Nice.