Saying all of this, I've just realised how new #PlainApp is. Its Reddit was created on 14th April and all of the open issues on its Gitlab are newer than 18th April...
https://github.com/ismartcoding/plain-app/issues
https://www.reddit.com/r/plainapp/
https://github.com/ismartcoding/plain-app/issues
Also I've just discovered #PlainApp, which is similar to #ShareX in that it uses your LAN or WiFi to share files from your phone (via the app) to your computer (via a web browser), but it can do a lot more as well like make #Markdown notes, and send & receive SMS messages and phone calls.
If PlainApp could run via my phone's mobile hotspot -- like ShareX can -- that would be a real benefit as it would remove the need to be connected to the internet.