Two circuits in same junction box?
Yes, that is fine. The only restriction would be mixing voltage classes. You couldn’t mix line voltage and low voltage (e.g. 12 volts) in the same box.

You can interconnect the grounds or not. If the box is metal and the conduit is not (or no conduit), you’ll need to tie one or both grounds to the box.

Be careful not to mix or interconnect the neutrals or hots.