I just discovered Starship, the cross-shell prompt, which has support for docker context

Starship is a really nice, fast, customisable shell prompt - of which there are many - but Starship supports a very wide range of things out-of-the-box.

Including docker context's. It detects Dockerfile and docker-compose.yml/yaml in the directory, and if you're not on the default context then it'll show the name of the context you're on in blue alongside a little whale icon. A tiny but very useful feature.