What is the minimum that has to be backed up on a cryptocurrency wallet (technically)?
technically the minimum you must backup are your private keys.

Is the seed enough? if you used a program which generates a wallet by a passphrase/seed it should be enough to save the passphrase/seed. test it to be sure.

i don't think you must really backup your public key or adress because it can be generated by your wallet with your private key/passphrase/seed.