You can mine Verus with them and and other ARM cpus.
https://veruscoin.io/get-vrscI have the the rock pi 4b and you can get 3 to 4mhs at 9w. Its about $.10 a day but its my staking box too, making $4 a day all for less then 10w.
I think this coin is CPU friendly, I visited the site and planning to mine some verus coins soon.
Glad to see that you are earning good with less electricity consumed. By the way thanks for
sharing. Cheers!