satopenpli

...whereas LTS kernel like the 5.15 have support for X years. LTS kernel are mosly used in commencial enviroment because it is more important to have long support then a high update frequency.

LTS kernels are updated as frequently as non-LTS one.
5.15 branch is on version 5.15.53 as we speak, last update was two days ago.

From what I read in Edision source code, they dumped 5.15 release in github 8 months ago, without any of subsequent 53 updates. Even though its simple to keep it updated, API is guaranteed binary compatible within the single kernel branch: rebase, test and move on. And mainline kernel developers are pretty specific with their recomendations "All users of the 5.15 kernel series MUST upgrade."

Just for the interest, in what purpose do you want to use it? If Sat-TV is necessary then about RPi4 is answer (still) no. Maybe one day it'll change.

I want a frontend multimedia box, that keeps getting updated (kernel AND userspace features) for as long as hardware itself lasts, 10 years is OK.

But it seems general situation with SAT hardware is pretty horrible, to put it mildly.

USB cards are almost non-existent, have out-of-mainline drivers and are overpriced as hell.

PCIe situation is a little less sucky, but need bulky x64 box for that.

Choice of SAT>IP devices is minimal too, pricing quite bad as well.

SBC market is OK, but every device is rotting without kernel updates.

Perhaps optimal approach would be to pick cheap STB, install SAT>IP daemon and then firewall and hide it in attic, out of sight.