"who do not have either W2 or 1099"

A bit of precaution...

W2: watch out for those that bring you a W2 because they paid themselves through payroll, but are operating as a Sole Proprietor or Single Member LLC. You might want to read up on how to unwind that error.

1099: you don't need a 1099 (NEC or K). What they need to do is give you their total business financial activities, not just the 1099 data. If someone wants you to file for their business activities using only their 1099 reporting, you need to do some due diligence.