NIP-07 extensions and NIP-55 signers are pretty good. NIP-46 is less good IMO (too slow). Delegations will never work (IMO). FROST might work, but it is quite complicated (managing keys for each app/device etc)
It is overwhelming indeed. But no protocol is perfect. We shouldn't be trying to solve all of it in one. The goal is to find a set of decisions in each of those buckets that work so well together that can 2-10x Nostr even though we know they are not perfect.