That was how they did things back during the ST days with a fair chunk of the tie-in media only being there to support the cinematic releases. Since then though, they shifted publishing to focus mostly on the High Republic initiative. I suspect the latter is probably the better approach since it frees up the authors to do mostly their own original stuff rather than always just feeding on the scraps left-over from the live-action projects.
I suspect the main reason we haven't gotten much tying into anything from the Mandoverse largely has to do with Filloni and Favreau needing to approve and oversee anything dealing with their characters, and they're very busy people. Indeed that need for close coordination may be one of the main reasons publishing broke off to focus on a whole separate era to begin with. The only time it really worked well in the past is with the 'Rogue One' tie-in books, and I suspect that came off mostly because it was an even more collaborative effort all-round than usual, so not everything needed to go though one or two people. Also likely how 'Rebels' was able to dovetail with that project so seamlessly.
At this point I suspect Favreau might not want to define too much about Dyn or his backstory beyond the stories he's telling. Even the stuff like the destruction of Mandalore crosses over with Ahsoka & Sabine's backstory (mid-story?) and Filloni might want to tell some of that in season 2. Oh and I wouldn't be shocked if whatever the next animation project they're doing has some kind of connection to that part of the timeline too, so that whole era may be ring-fenced for now.
On the non-fiction front; word is that the ST visual dictionaries and crosssection books didn't sell all that well, which is why they pivoted to combining them into the visual guide format used for Rogue One and Solo. Indeed, they did put out just such a one for some of the Disney+ shows fairly recently in the form of the '
Dawn of Rebellion: Visual Guide', which lumps together Andor, Kenobi, Rebels, Bad Batch, Fallen Order and other related projects. One assumes if that sold well enough they're probably already putting together a New Republic one to cover the Mandoverse thus-far. I'd say there's a non-zero percent chance that it may already be ready to go, but they're holding onto it until 'Skeleton Crew' is out later this year.