Accessibility services can really improve the experience of using our phone. I couldn't handle today's enormous phones without Edge Gestures and Quick Cursor, I really feel handicapped without them. Although I do have two hands, I'm just used to using phones one-handed. Wasn't a problem until screens got too high and wide...
Then I use Universal Copy to copy any text on screen, something Pixel UI offers natively. Enormously useful, wouldn't want to miss it.
With anything you run on any computing device, there's always the question: can I reasonably trust this code? And there's always the trade-off between security and convenience. Sucks, but that's how it is. Luckily we can at least disable network access for those apps that don't need it (if they ask for it in the first place) on GrapheneOS.