“For instance, I often had to rely on the web browser to access services like Reddit, Telegram, and Discord since native apps weren't available. Web apps work for primary use but can't always replace dedicated apps, especially for banking or fitness tracking.”
That’s the core of the problem these days. Nowadays, there’s so much that requires an app to work.
Avoiding mobile apps was entirely realistic in the 2010s, but it’s too late for that now. The world has changed, that ship has sailed etc.
If you can isolate yourself from certain realities of the outside worlds, using a fully FOSS system can be done. The technology is there. It’s just that most people can’t isolate themselves to that degree.
My bank warned that they are planning to phase out the code booklet and replace it with a mobile app. Sure, you can continue to use a web browser, but how do you verify anything without a mobile app?
Also, some apps are very picky and refuse to work properly unless your android has GAPPS and is in the in an unmodified state just like the OEM intended. That’s bad news for privacy oriented Android users, let alone anyone who wants to run something even more FOSS.