So I would open my Shelf app, pick TinyTally and get going, but at the same time I could also pick other TinyJS apps and run them each in their own TinyJS environment.
Have you thought about this? It's kind of a weird idea, but it could solve app distribution on every desktop OS actually. I'm on Linux, but it sucks to install and we never know how to distribute desktop apps here. I imagine it's also pretty bad on Windows and MacOS unless you pay the heavy amounts they require for their centralized app stores.