Why Bedrock? Get the kids a Steam Deck, Prism Launcher, open a local server and boom :) It‘s not iOS convenience but they‘ll sure love to tinker with all the mods you can install.
Alternatively one could spin up a local Java Edition server and install GeyserMC translation layer plugin[0] into it. That way, both iOS and Linux PC could cross-play to each other without the need of another new device.
