Well, if you can't trust the machines (PC) or the Android devices for the air gapped purpose, you can use the simple USB, install the tails OS software, never connect it to the Internet and you're good to go. Electrum becomes built-in in the tails OS but you will need to manually install the Sparrow wallet. I do not know if it is possible or not as I haven't experimented with the Sparrow wallet.
And, if OP doesn't trust the Electrum installed on Tails OS or simply prefers BIP39 seed instead of Electrum "flavor", he can use the stick for the OS with no storage, but use /dev/urandom and Ian Coleman's page (copied to that stick or another one) like explained here:
https://bitcointalk.org/index.php?topic=5475496.msg63228430#msg63228430