This just shows that the barrier of entry of a new phone OS is more than $0. You can pay app developers to port their apps off of play services, you can pay developers to add support for your attestation keys. Considering how many billions of dollars Android makes for Google, there is a room for a return on investment for an alternate OS to enable investments into a new OS.
That's akin to creating a new browser and pay site owners to support your client. You can do it for a few dozen sites but that can't be your primary strategy.
We actually saw this play out twice with Microsoft's return to mobile (Windows phone) and web browsers, money is a pretty small part of it.
How much do you want to pay? Who will be paying? Big companies will probably laugh such an effort out of the room, nay, they will not even let you into the room to talk with them.
an additional anecdote from my time then: they came to where i was working at the time and proposed funding a windows mobile version of our app (quite a large sum) but our supervisor finally said no, because the upkeep of now 3 apps would be too much for too few customers
you cant just throw money at devs and expect much unless you have the user base (potential market) to back it up