thank-you!
If the gs290 began with official-/e/-OS in 2021, the OS would be maintained up to 2025 by /e/.
I did not found any mention of gs290 in : lineageos devices
(Lineage is adapted to about 200 phones models).
Probably Gigaset did not made any update to android-13 for the gs290, as you point.
This is the reason for the other post : murena-smartphones-life
There are not so much recent phones to benefit of official-/e/-OS. (in december 2021, the price of the /e/-gs290 was 230 €, may-be I could use it until 2026).
Brieucs.