I have the same problems and it enraged me. It enraged me to the point where I back flashed the nvidia and blocked all domains to .google.com at the pihole for that mac address. Above that all NAT for DNS and blocking DoH and DoT. I do not need "new firmware" versions as the software I run on nvidia shield is just fine.

I unlock the shield, manually install the apps I want updated and ignore the rest. It has no external internet so meh if its got zero day exploits open.