Author here: I think the main problem nowadays is that most of the Android devices sold on the market are running a heavily customized version of Linux (and in most cases incredibly outdated too).
Some (newer) Android devices seem to be migrating to the "AOSP Common kernels" / "Android common kernels" [1], but I doubt this is that common outside of the Google Pixel devices.
Until the manufacturers (e.g: Oneplus, Xiaomi) will start using a close-to-mainline kernel (and distributing the sources!), we'll just have to hope that the amazing people who contributed to support arm64 devices [2] or simply porting devices to mainline, will keep doing so. Of course anyone is free to contribute - but it would be way easier if the manufacturer themselves started to help towards this goal.
Having said that, and assuming good mainline support (to be honest, for me it's enough to get access to the storage, CPU, network), my old devices generally come with a somewhat powerful octa-core SoC that can handle workloads better than my Pis. I would have to benchmark them to support my claim, but already having 4 more CPUs helps - despite they might be in weird configurations (e.g: big.LITTLE [3]).
Some (newer) Android devices seem to be migrating to the "AOSP Common kernels" / "Android common kernels" [1], but I doubt this is that common outside of the Google Pixel devices.
Until the manufacturers (e.g: Oneplus, Xiaomi) will start using a close-to-mainline kernel (and distributing the sources!), we'll just have to hope that the amazing people who contributed to support arm64 devices [2] or simply porting devices to mainline, will keep doing so. Of course anyone is free to contribute - but it would be way easier if the manufacturer themselves started to help towards this goal.
Having said that, and assuming good mainline support (to be honest, for me it's enough to get access to the storage, CPU, network), my old devices generally come with a somewhat powerful octa-core SoC that can handle workloads better than my Pis. I would have to benchmark them to support my claim, but already having 4 more CPUs helps - despite they might be in weird configurations (e.g: big.LITTLE [3]).
[1]: https://source.android.com/docs/core/architecture/kernel/and...
[2]: https://aarch64-laptops.github.io/
[3]: https://en.wikipedia.org/wiki/ARM_big.LITTLE