Can't make it boot on rpi4 SSD only

I want to install start9 on a rpi4 or on an odroid m1, with SSD only on the rpi or on the ssd m2 on the odroid m1.
I tried on the rpi4, flashing as usual the image to the SSD but it will never boot, seeing the led lights it seems to go on an ethernal loop. On Umbrel for example I used to install debian then run a script that would install umbrel on top of debian, is it possible?
On the odroid m1, I could install debian or ubuntu than run such a script also.
on the rpi4 I tried the image for the rpi4 but also the arm iso, but both had the same result.

Unlike Umbrel, StartOS is an advanced operating system, not a set of apps installed on top of someone else’s operating system.

StartOS expects certain things to be a certain way, as it’s designed to be run on hardware that we test on and that we sell (on in the case of the outdated Pi4 - sold).

What you’re attempting isn’t possible with StartOS, since we don’t recommend unpowered external SSDs at all as the Pi4 isn’t capable of properly powering them. As such, no time has been spent on developing a way to do what you’re trying to do.

Maybe just run Debian and install the software you need on that?