iodéOS has official support for the Galaxy Tab S5e, which is on the list you linked. I own one but I don't use it for art so I can't comment any further.
The support is fine. It doesn't have 5G because it is not a 5G device (and one model, the WiFi one which I have, does not have any cellular capability). It doesn't support VoLTE or bootloader locking because it is a Samsung device (you always lose these features with Samsung devices unless the ROM is based on OneUI). It doesn't support the automatic iodéOS installer because, again, it is a Samsung device - you have to use Heimdall. I'm not 100% sure about the firmware bit. I believe that is referencing whether the ROM includes the latest manufacturer firmware update as well, but I can't say for sure.