It's a good idea in concept but tons of popular libraries use async which makes it difficult to avoid. Want to do anything with a web server or sending requests, most likely async for popular libraries.

Yeah, the nom asynch nats client got deprecated for instance. It really is a shame, because very few projects will ever scale large enough to need asynch, and apart from things like this, there are costs in portability and supply chain attack surface area when you bring in tokio.