The only developer that knew how to integrate dvb drivers in coreelec has gone missing around 2 years ago, so the reply to every question about which tv-box to buy with integrated dvb tuners is “buy a sat>ip solution”.
But I also know that availink is actively (I think, there are recent commits) maintaining several repositories on github and they say
We package the drivers into the CoreELEC distro as a proof of concept
Availink isn’t the only game in town, but many (most?) tv boxes use their products, so what happened with them? Did they reach out to you? Did you try to contact them?