A few hundred jobs a day doesn't seem like it would even be close to what postgres could handle easily, does it?

I'm thinking of the problem as using a small amount of text to represent the work that needs to be done and then using a postgres table where some entries are being added as work that needs to be done, and then a worker is pulling the rows of work out of that table, and maybe putting a completion message somewhere in postgres. I'll concede that is more transient data than probably most of the other tables, it might benefit from vacuuming more often. Does the autovacuuming system not figure out it needs to run more often and do it?

Wouldn't the issue would be more overall queries per second, the amount of writes you're already doing, and the general load on the database. We just added some audit tables that are quickly growing to millions of rows, and it seems like Postgres isn't even breaking a sweat. I'm mostly spit balling here and probably glossing over some details.

But, like you said SQS is pretty easy too.