I agree, Flotilla could gradually teach people about remote signing, i.e. using Flotilla's affiliated apps (Coracle) - "Now try to login to Coracle using this bunker-url etc". And then users would probably try to login to other apps. And then after a while you could explain that users should migrate to non-custodial signer so you could reduce risks for the user and yourself.
I wonder though whether we're shooting ourselves in the foot by trying to make the learning curve less steep... Instead of teaching users once "here is how you use Nostr - get a proper signer app and put keys there", we create these longer multi-step long-lasting flows which might create more confusion in the end. Still not clear to me where the balance is.