If I understand correctly, joplin proposes no web app, though the desktop client is an electron app, so it's ultimately a web app. Then it shouldn't be too complicated to build a web app, should it? There might be something I'm missing?
In the past, there seemed to be an unofficial web interface that's now defunct on github foxmask/joplin-web/tree/vuejs (blame discourse I'm not allowed to create a link) though, but an official web app is (IMHO) a must-have
I remember joplin has an embedded sqlite database, so it can't run in your browser, You might be looking for Trilium Notes.
I remember joplin has an embedded sqlite database, so it can't run in your browser
We might be able to use sqlite-wasm or absurd-sql for this. There might be other components that are difficult to port to a browser though.
What special features that are stored in the sqlite db? Can't they be bypassed/ignored? Anyway, sqlite can be run in the browser nowadays, see for example "franchise cloud app" (still can't include links…)
Hi and welcome @ Joplin! 
You can do a search on this topic and you‘ll find answers quickly 