I mean I'm using PlanetScale with Prisma ORM on AWS Lambda right now without issue. Unlike many DB providers, PlanetScale supports nearly unlimited connections. I think I saw in their docs they have a soft-limit of something like 250K connections.

I used Aurora Data API before moving off Aurora Serverless (insane pricing) to Prisma and PlanetScale, I don't think I'd go back to the HTTP API as Prisma works very well and I enjoy using it. One downside to Prisma is the DB "engine" is a arch-specific (obviously) binary that is pretty hefty. I want to say ~50MB. That can be a killer in serverless but I was able to work around it without much issue. If I ever wanted to dive into the world of Lambda layers I could probably move it into it's own later (however that still counts towards your max lambda size).