From my experience, those aren't users determined to use outdated smartphones.
These are the super shady cheapo TV boxes that are essentially an underpowered SoC + Android 4.4 + a launcher. Or many Chinese handheld gaming devices.
Users probably do not stick around with 4.4 given how many important apps would not work.
As far as I know it's also used on embedded devices like barcode scanners at Tesco. Those either run Windows or Android. Ancient versions in both cases. Unfortunately it seems the model number disappeared from my search history so I don't know which versions for sure. I think it's either Android 4.4 or Windows CE.
But in those cases the Google Play services probably don't matter.
Nearly 2 years ago (Sept. 27th 2021) they removed sign-in support for Android versions <= 2.3.7 and nearly 3 years ago (Sept. 20th 2020) they removed YouTube web app support for Android versions < 4.0.
The latter is kinda sad. That YouTube web app opened videos in the browser's video player and it didn't support Ads. Yep, you didn't even need Ad blocker.
Unfortunately I don't have the original screenshots, just this image I quickly put together for something, but it partially shows the simple (good) YouTube UI: Image link for compatibility