I've written many lambdas in Python but have switched entirely to Go for all my new lambda work. Go is just better in every way - uses a fraction of the memory and executions take a tiny amount of the time Python takes.
re: full serverless:
I mean, try for yourselves but unless you're running an echo statement, you'll probably be hard pressed to get lower than this. Some early experiments with Rust showed 5x that, and that is as close to GO as I would dare to compare.
It's probably not the same test but python is still at the top [1]
[1] https://www.simform.com/blog/aws-lambda-performance/#Startup...