Find a company that does both, and that will hire you for your experience in one. Maybe that's a Python company that needs to do Rust stuff, or occasionally has performance constraints that mean they need to use C?
I did this with a consultancy a few years ago. I did some Symfony work for a client they needed help with, but there was an (honoured) agreement that after that I would never have to do PHP work ever again. After that I moved into Python & Golang work.