If you want to export your Keep notes (and almost all of the metadata and media) into Markdown format, I helped write keep-exporter, a tool to accomplish just that.

It downloads the text content of the notes and the majority of media (some of the annotation stuff doesn't work quite right). So assuming another app supports markdown import, this would work.

https://github.com/ndbeals/keep-exporter/

(note, the version in PyPI is behind and I don't have access to update it, so pull from the repository instead)

It uses gkeepapi (https://github.com/kiwiz/gkeepapi), but it looks like there's an official API now (https://developers.google.com/keep/api), so maybe Keep isn't going away anytime soon.