New Discourse User - a few questions

No, there isn’t an official one. You can use a PWA as a desktop client. There are unofficial ones like A Social Mobile & Desktop Client for Communities (2).

If you are using the free plan, I don’t think you can disable it.

Self-hosting is pretty easy, actually. It’s mostly just a one-line install if you want the basic installation. Take a look at Documentation > Site Management and Documentation > Self-Hosting . If you have more specific queries, feel free to open a topic about it.