Can any brand of solid flat tappet lifter be used with any brand of solid flat tappet lifter cam?

Intended for use in the same engine?
Probably.
Between engines?
Less likely.

Yes, same engine and the engine hasn't been run yet so the lifters I have are unused. Just wondering if I can use a different brand of cam than what the lifters are.

Only a few companies made / make lifters, regardless of which cam company's name's on the box.

the cam grinders don't make lifters of any type. they just package with their name on the box. most flat tappet performance stuff is johnson. talk to howards and pretty sure they'll tell you yours are johnson lifters. pretty sure comp cams use johnson. second tier cam grinders may or may not use offshore or mexican lifters.