If I understand your question correctly - these are my thoughts...
1. If you are a W2 employee at a facility, it is typically discouraged that you pick up shifts at that facility through Nursa. The facilities themselves do not allow that and if they catch wind that it's happening, there are usually consequences. Of course, that's up to the facility themselves!
2. If you are a W2 employee somewhere, you are totally able to pick up shifts as a 1099 and file your own taxes in addition to your W2. I've never had any issues with that! And on the flip side, if you are picking up shifts as a 1099 via Nursa or another platform, it doesn't prevent you from getting a W2 job.
Hopefully this is helpful! haha