Hi @nathanguyette,
what you are asking should already be possible.
You could create a freelancer@nathan email, add it to your anvil team and send the credentials to your freelancer. Then add him as collaborator for the respective project. Not sure which plan is required for permissions though.
After the job is done - change password and the seat is ready for the next job.
One thing I would certainly love to see is more fine grained permission control. Who can merge into master? Publishing? Change Environments…
Enabling Pull requests would be a killer feature for larger projects as well.
But I got a feeling this is something that anvil.central will want as well.
Greetings - Mark