It sounds to you like nothing short of fully self-hosted fits the bill? I think it's pretty clear what they're doing: Libre SaaS. Of course you have to trust t

It sounds to you like nothing short of fully self-hosted fits the bill? I think it's pretty clear what they're doing: Libre SaaS. Of course you have to trust them with anything going in clear-text on their servers. But you don't have the vendor lock-in you'd have with proprietary alternatives. It can be a great bridge between Google/Apple/Microsoft/etc and self-managed, if nothing else.