If you know me, you won't be surprised that I find this highly disappointing. It's a deeply held belief of mine that if you own a device, you should be the one ultimately in control of it. Even free software isn't practically enough to make this a reality, because having access to the source code doesn't mean it's straightforward to modify a program if it doesn't work quite the way you want it to; affordances for users to modify software haven't been common since the type-in program days of the 70s and 80s. But this goes beyond even modifying your software, to preventing you from installing unapproved software altogether!
The unfortunate thing about this situation is that our available choices are steadily closing. Today's society more and more expects you to carry a smartphone around with you all the time, and practically speaking, that phone is almost certainly running either Android (with Google services) or iOS. iOS has already been locked down since its inception, but we're about to be in a world where (with few exceptions) you can't run software on a smartphone without either Google or Apple's blessing.
Let's talk about those exceptions a bit.
There are several third-party Android distributions, like GrapheneOS, CalyxOS, and /e/ OS, that certainly won't follow Google's lead on this. The percentage of people using these alternative distros is and will probably always be very small. You can't walk into a store and buy a phone running them. You can buy them online, but you have to go looking for them. I would guess that most people running these alternative distros install them themselves, which takes some (not excessive, but some) technical skill.
More importantly, these projects exist in the first place at Google's whim. They're all based on AOSP, the open source version of Android, which is a Google project. Android isn't developed in the open, it's thrown over the wall when Google announces a new version, so there isn't a healthy community of third-party contributors ready to take over. If Google decides they no longer want to release new Android versions as FOSS, that would likely be the end of AOSP as we know it, and all these projects with it.
So Android is in a precarious state. What about mobile Linux?
The various mobile Linux projects are getting there, but largely suffer from both a lack of contributors and shifting carrier requirements over the years that they've had trouble keeping up with. On the plus side, the mobile Linux GUIs have gotten very nice and the app ecosystem is impressive when it comes to the basics - we've come a long way in the last few years. It's beginning to feel a lot like the old N900 days. :)
But a quick rundown of the dilemma I've run into with these:
Group texting
VoLTE
All day battery life
Ubuntu Touch handles this best, because it suspends apps in the background and relies on push notifications. It sips power while idle
Plasma Mobile supports push notifications through KUnifiedPush, so they could hook up a similar power profile, but to my knowledge haven't yet
The two devices that I know support VoLTE without OS support (Librem 5, PinePhone) also have higher idle power draw, relying on suspend for decent battery life. You can't receive messages on internet messaging platforms while suspended, which is a dealbreaker for me since most of my messaging is on Matrix these days
Other Qualcomm devices might have decent idle power draw even without suspending apps? I don't have direct experience with that yet. (I'd be interested in hearing your experiences with this! If you use Matrix on your Linux phone and have good battery life, shoot me an email)
The FuriLabs FLX1 looks interesting, but I don't have one myself. In general I'm wary of mobile Linux distros that are tied to one phone vendor (historically they've had poor staying power in the long run) but it seems like it might check all of these boxes. Also interested in folks' experience with that device if you have one.
In the long run, I think mobile Linux will have to be the way forward if we don't want to rely on Google - and I don't think we can rely on Google in the long run. There's a lot of work left to get mobile Linux ready for the masses, but there's also been a lot of work done so far. We need a third option, because soon neither of the two major operating systems will let you write and run your own code without their approval.
Especially if you're a developer, give what's out there now a try. You might be pleasantly surprised already! And we need more folks working on these and building software for them, so they're ready when they're really needed.