First, I am a beginner.
I have the GX290. IIRC the differences aren’t that big compared to the supported GS290.
Is it possible to install e/OS on my device?
It currently runs Ubuntu Touch, but I am dissatisfied with this OS.
Do you still have the file e-0.23-r-20220512-UNOFFICIAL-GX290.zip?
Yes, e-0.23-r-20220512-UNOFFICIAL-GX290.zip
Here the link some people are still searching for.