i believe it's non custodial and open source yes, nostr:npub1s33sw6y2p8kpz2t8avz5feu2n6yvfr6swykrnm2frletd7spnt5qew252p has a good video on it.

I haven't used other teather wallets so wouldn't be able to compare . Aqua has teather on liquid , Eth and Tron tho