Doesn't that require a much higher temperature than most beds would be able to safely achieve.
I had to take the screen off of a Pixel not terribly long ago to replace the battery. I used a heat gun and I remember it requiring a temperature of like... 240C° or some such? And when I'm printing PLA, my printer bed only gets to 60C°. (Not saying it couldn't go higher, but 240C° seems way higher than 60C°.)
No, that temperature would damage your screen. The professional hot plates for phone repair are typically set to 85-90°C. With a heat gun you may need to set a higher temperature since you are only heating up part of the phone and it cools down again during the process.
My printer (Prusa MK3) with PCB heater can go up to 120°C, so it looks perfect for the job.
What I've used for this purpose is one of these. And I can attest that 60C° is nowhere near high enough to set that kind of thing for purposes of getting a Google Pixel 3a off safely.
But I bet ThetaDev is right that a flat plate heater can work just as well when set to lower temperatures because they heat the whole screen at one time.