If you have Chromium installed, you can install tmpdir as a Chromium app:
Then (at least in KDE), it will show up in your menu->Chromium apps.
You can also do something similar in Chrome on Android. Open site in browser, click on menu, and look for “Add to home screen,” “Install app”, or “Open TMPDIR”. After that, you should be able to add a launcher button to one of your screens if its not already there.
Thanks for sharing @cbrake I use discourse app on iOS and that works ok too, although I prefer deskop for any writing job on tmpdir.