Linux

I think either PostmarketOS or Mobian would be the best existing candidates right now.
Hardware wise, the Fairphone 4 is probably the best option, especially compared to something like a Pinephone.

I tried Phosh (Gnome mobile shell) on an exhibition a while ago and honestly loved it.

However, I'm absolutely not confident in those tbh, in terms of reliability. The whole thing is highly experimental right now, and I wouldn't trust them as a daily driver.

Phosh is also available for Fedora, especially Silverblue (available as ARM iso), since you are, with me together, probably one of the most prominent Fedora Atomic fanboy :D

I see big potential in a uBlue-phone spin maybe. I tried making one myself, but I absolutely don't have a clue what I'm doing and don't want any responsibility for such a project.
Do you know if or how we could organise such a project?

To which project would you give your money to accellerate it?

I would reign in your hopes of accelerating a project using money, unless you have enough money to pay someone's salary for a significant period of time.

That said, I'd suggest postmarketOS or Mobian might be the most worthy of donations.

https://mobian-project.org/

I love my Pinephone, not enough to use it as my main phone thou.

It's running Mobian, mostly because everything else I have is running Debian in some form, but it looks like the largest project is PostmarketOS.

I found Ubuntu Touch/Droidian the most promising when I last tried to get a good Linux mobile setup. Everything was working and i could run any linux app i wanted. The only problem was mobile data configuration with ISP here in the UK. I would donate to whoever is making the best progress and having the most impact. There is so much variety of hardware with phones that a single (or very small number) of compatibility layers needs to emerge.

@GravitySpoiled
I'll trying to buy a pine phone as my first Linux phone as it's cheap. Not great but would be okay for tinkering.
@linux

When I was looking a couple years ago Ubuntu Touch was by far the most developed and stable. Primarily because Canonical poured millions of dollars into its development before giving it up and dropping it, but the community has gone a long way to make it what it is today.

Probably not a popular choice on this community though.

In my opinion postmarketOS is the most promising mobile Linux OS now. But the phones? Only OnePlus 6 is good. PinePhone is a project to look at as well but the hardware is not as good from the regular user's perspective