I saw @moneyball post about Photon SDK on X. It was made by @tankredhase (on X) in 2022 (it was for lightning back then, but looks like it's an onchain thing now) but looks similar to the Bitkey model of seedless backup.
App developers can build compelling seedless user experiences using encrypted cloud backup and multi-sig.
The SDK is open source and includes a key server, api, react native client and a demo app.
I'm torn on the seedless idea. Bitkey makes it very difficult for users to extract their private key data and in a panel at Bitcoin 2025, Max Guise, from Block/Bitkey, said that wallet portability could mean "sending to a new address." This feels a lot like vendor lock in to me.
On X, I pushed on the question a little bit: do Bitkey users have to use Bitkey electrum nodes? Can Bitkey prevent users from signing or broadcasting a transaction? And the answer seems to be negative in both cases. But it's not exactly easy. Users have to download an emergency recovery kit from a github repo and sideload it on their phone and a lot of the redundancy goes away (if you are in a situation where you cannot access Bitkey's services AND you lose either your phone or your Bitkey device, you are screwed).
So, if this SDK is similar to Bitkey, I hope it allows users to export key material more easily. How do stackers feel about seedless?