What aspect of HR are you thinking of?

Recruiting? (Probably shouldn't be considered an HR function in an SMB.)

Benefits? (Probably taken care of by your HR platform like Justworks, at least at a small enough company.)

State compliance training? (Like the yearly required sexual harrasment training required by NY state. Hopefully covered by Justworks or similar platforms.)

Diversity and inclusion? (Better addressed by all hiring managers/top down rather than just left to HR.)

HR can be a broad category of "things managers don't feel like doing" and some things you are legally required to do.

Since you didn't mention any examples it's hard to know which parts you're thinking of.