I’ve only used blue wallet as a watch wallet for my node’s lightning. But if it’s giving you seed phrase you should be able to input that into other wallets, almost any non-custodial wallet. Blue Wallet might have stopped developing? Haven’t heard much about them for a while.
For non-custodial I’ve heard Phoenix and Alby being recommended. Good questions. There should def be a push to do self-hosting with the senator Warrens of the world trying to have a say about what we decide to save.
Cheers!