Not with Umbrel. You’d need to rebuild the docker containers and since 0.5 they redid everything.
There is no documentation and no Dockerfiles that I can find.
You could achieve partial improvements by changing the docker-compose.yml
But if you run a big node in the home, I’d use Rasbibolt and definitely not on a RaspberriePi.
I am currently working on a guide for running a node redundantly on more than one computer.