groche

No. The main diference is that you write a software for Android, it doesn’t work in gnu/Linux (without extra layers), but if you write a software for steamOS, literally you are writing a software for gnu/Linux. SteamOS is an arch Linux modified to be immutable with a custom (and free) kernel with extra support that they merge after in mainline, with the steam app oppened by default. SteamOS use all the software stack for gnu Linux. Android develop their own stack and work different.

afro samurai is a masterpiece

But you want to use systemd-boot? Obviously you need to install systems-utils if you want to install systemd-boot, but you can use grub or something else bootloader

You can install gentoo-kernel-bin and everything works fine. About SystemD, you needn’t systemd as init, but you need systemd as udev or other things. Only follow the guide with a non-systemd profile

Nowadays a lot of hardware works very well on Linux, the main approach of this vendors is not the compatibility (has guaranteed but as you say in a thinkpad you have the same compatibility), the approach is about a free software (or mostly free) firmware, and in this case, free and secure implementation for the firmware an all secureboor chain