Buy a last gen Pixel used from a private seller maybe like on eBay and install GrapheneOS OS on it. If you don't want to mess with a lot of stuff, you can use the main profile for foss apps and open another user in which you install sandboxed Google Play services and gradually switch to foss apps more and more
Anything and everything else is objectively worse than an iPhone
"Don't theme my app" is all about distro defaults. No one is arguing against user modifications as long as the users don't expect any official support for their custom stuff
My SIM provider has the option to not even route unknown callers to my device. Not that I get any, but just in case, even if it is not that common in Germany.
What some family of mine had to go through was social engineering harassment calls with some BS reasoning to get them to say "Yes"/"I agree" or something like that
I would really recommend you take a look at ProtonDB when it comes to troubleshooting like that, it is one of if not the best resources for that kind of stuff
I found virtual box so much more confusing than virt manager TBH. Also there is GNOME boxes which is just a pleasure for spinning up quick uncomplicated VMs
TBH I don't think I will ever even consider using Cosmic since they chose to do their own thing theme and ecosystem wise. Like on Gnome I have a massive ecosystem and GTK4, so that blends. On KDE I have a massive ecosystem and QT, so that blends. On Cinnamon I have a moderately sized ecosystem and GTK3, so that blends.
My Cosmic desktop would just be incoherent mess. Not only looks wise, but also in terms of having an experienced dev team and mature software.
Maybe in five years I might consider it production ready and for actual use on my workstation, until then, I will just keep rolling my eyes at the literal "we remade everything in Rust" meme.
Also I don't feel comfortable using software from a company that has shows extremely shitty behaviour towards upstream in the past.
There is a big blue button that would allow them on the respective site