Is it possible to convert a node red flow into a application or a .exe file
Take a look : https://www.electronjs.org/apps/node-red
Have a look at the excellent https://github.com/dceejay/electron-node-red to generate an .exe application.
Note - I have never done that so no idea if it possible ...
[edit] - just had a quick look - and there are zero docs on how to get electron builder to build a suitable apk... the word apk is mentioned - but no examples - requirements for headers, manifests etc... so if anyone figures it out please let us know.