That's not how electron apps works. When you load a website with your web browser you get served the front and execute it. When you have an electron app, the front is in the source code of the app, and you decide when to update it so you don't get served unexpected compromised updates. As for the paid service : They don't sell your data and don't show you ads so they need money, it's that simple.
I already answered that. Yes you can't trust a website's content, that's why they offer apps. It's your choice to trust the website which is as secure as they can make it, or you simply use the apps...
I'm not sure what you're talking about ? You're not sending your private key to their server without first encrypting it first locally. Their servers are not doing the E2EE, your client is. The website front and apps are open source.
Yes they could send you a compromised front if you use it via their website, that's a compromise you accept, otherwhise you could only use their apps which are open source.
In my opinion, those warnings are not used to help users but to shame developpers for not trully sandboxing and verifying their apps. Developpers know that having this warning will decrease the number of users downloading it. The goal in the long run is to improve app sandboxing and security.
The browser can lie all they want, at the end of the day the user has the final word if they want to change things.
Why wouldn't it be my browser asking for the codecs it prefers instead of the website trying to guess my computer's hardware ?
RedoxOS >>> It's written in Rust and is learning both from the success of Linux by being source compatible with it and from smaller/experimental OS like Plan9, seL4, Minix and BSD.
RedoxOS, an open source operating system written in Rust that aims to improve correctness and safety by picking up innovations made by experimental operating systems over the years while not reinventing the wheel and trying to be source compatible with Linux.
QubesOS, the most secure open source operating system making it easy to use security by virtualisation, splitting your activities, peripherals, drivers into different virtual machines.
If you're interested in Meshtastic, take a look at Reticulum : https://reticulum.network/