It is shaping up to be a good year for phone freedom with two phones capable of running mainline GNU/Linux already shipping.
The two phones, namely the PinePhone and the Librem 5, are developed and sold by two different companies. They differ considerably in terms of price, hardware and software choices, production methods, etc.
The models currently shipping are in a very rough or unfinished state and so at this stage are only suitable for hackers and early adopters who expect an unfinished product.
Both phones contain proprietary modules (e.g. WiFi, Bluetooth, cellular) but the manufacturers have made efforts to isolate them from the main processor and included physical kill switches for untrustworthy components.
With the help of the free software community, efforts are ongoing to make desktop GNU/Linux applications display correctly on smaller screens as well as to port desktop applications to phone-oriented operating systems.
I am happy to share news of this exciting development in the mobile space, but I do not have experience with the phones I mentioned or the companies selling them, and am not able to make specific recomendations to anyone who wants to buy one of these products.