It is good to see the final part of their response
We want to be clear that we are not opposed in principle to de-Googled devices. The challenge is that, in practice, it is demanding to ensure both broad device support and compliance with the requirements we are bound by.
If Murena could be persuaded to adopt alternative attestation it might be possible to reach a compromise. A suggestion here Apps with SMS Authetification will not work - #4 by aibd