Time tracking software seems to be a popular app genre for PWAs and here's another cracking contender, Thyme, complete with import and export facility, multiple project support and cross-device syncing with online server access. I'm only scratching the surface of this online PWA tool below, so why not give it a whirl in your own life and let us know how you get on? It should work across Windows 10 Mobile, and all other decent browsers on any platform.
Of course, you can turn this into an 'app' yourself with PAWA or just pin it 'as is' on your Start screen. Or just add it as a 'Favourite'. It's up to you. If you're confused by the different PWA options then check out my feature here.
Thyme PWA is open source and if you're a web developer then you can get involved here to improve Thyme still further.
Here's Thyme PWA in action:
Starting and stopping time tracking on multiple projects. When you're done with a project for the day, you 'add' it to your record; (right) a login is free and easy on the Thyme server, syncing your stats and data to other logged in devices.
The Thyme hamburger menu and (right( browsing through the extensive help and documentation.
There's a lot to discover in the menus, not least export and import of data in .json format; (right) many of the reports are textual, but you can also generate pie charts - which will probably look a lot more interesting than my text example here!