Technically, every Android phone uses a "very bespoke AOSP", because the Android kernel is customized for the hardware of every single phone model, which can include things like hardware drivers and carrier services.
This is the reason that there is no universal Android ROM that works across every Android phone, unlike Windows or normal GNU/Linux distributions.
What about custom ROMs like Lineage? The only thing holding it back from working on every phone is that many phones have blocks to prevent installing a custom ROM in the first place. Could be just like windows in that it has every driver for every piece of hardware in the package, just bloating it unnecessarily.
The manufacturer has to release the phone's kernel source code before any custom ROM development can happen for the phone most of the time for that reason.
There is a reason that GrapheneOS only works on a couple of Pixel phones.
Could be just like windows in that it has every driver for every piece of hardware in the package, just bloating it unnecessarily.
Google specifically designed the Android kernel so that the driver are excluded, unlike the normal Linux or Windows kernel, because, long story short, Qualcomm did not want it to happen.
Every device had it's own device tree and kernel with custom driver's, binary blinds, and system software. All of it runs beside the closed source modern os
I’m not entirely sure because I’m not very knowledgeable about CPUs, but it seems this is largely a problem with ARM architectures and their lack of standardization, isn’t it?