I don't recommend using the vast majority of mobile apps, which exist for data-mining and addiction-maintenance purposes. Android is specifically known as the worst ecosystem in this regard. Browsers continue to work, despite the corporate push to dark patterns.
It's Linux, if you need something you or someone else will eventually write it. But first there needs to be acceptable, working hardware. Enter the FLX1/s, and we come full circle.
Sure, the majority of mobile apps suck. But even then, 1% of it is still orders of magnitude larger than the number of "Linux" apps, and there are surely more actually decent mobile apps than that.
Besides, open-source doesn't have to be GNU, there are a bunch of open source apps on F-Droid.
I also reject non-free apps whose main purpose is to snoop on their users like Facebook. But what about dozens of FOSS projects like Home Assistant, Jellyfin, Nextcloud, KeePass and many others? All of these have polished clients that work perfectly on Android and provide an experience that rivals or surpasses commercial offerings. They took years to develop and I don't expect Linux phone versions will ever be released because of the chicken and egg problem. You can emulate these apps with Waydroid on a Linux device, but you will almost certainly lose some features like GPS access or notifications. At the end of the day, you will mainly be running Android apps anyway, free or non-free, so you are better off with an Android device in the first place.
I currently use 0 Android apps, so honestly believe one could survive without them.
I'm glad Waydroid is a thing for folks that are, and sorry attestation prevents full compatibility. But neither issue should get in the way of investment in modern Linux phones, which I've been desperately waiting for, for years.
Web apps are still a thing as well, believe it or not.
It's Linux, if you need something you or someone else will eventually write it. But first there needs to be acceptable, working hardware. Enter the FLX1/s, and we come full circle.