Arm64 hardware compatibility

What arm64 system should I build/buy to test Rocky?
Pi? Strictly Pi?

I am currently running Rocky Linux 8.5 on a Raspberry PI 3B+ and it works very well. (I plan to do it on two other ones too)

I would suggest that you have a look at the official docs: Rocky Linux on Raspberry Pi | Rocky Linux Wiki

Nevertheless, I think Raspberry PIs ( are a great start for getting into Arm64. In particular the Raspberry PI 4 is a very powerful machine for less money. Unfortunately, it might hard to buy one due to the current chip supply situation.

Another option would be PineRock boards (ROCK64 | PINE64) but I am note sure of they are working fine with Rocky Linux.

Now a days we are testing AWS ARM base graviton2 instances with Rocky Linux 8.5. Its performance is looking far better than its equivalent x86_64 instances.