I tried a rig not entirely unlike that (not sure on the name but looked like maybe the same factory). The "precision" and repeatability was, in a word, terrible. I was more accurate just drilling by hand with a square stood up beside the bit to sight down. I'm not saying they all have this problem.. but the reviews on the wolfcraft seem to mostly mirror my experience (good enough for rough work, not so good for finish work).
What I ended up doing was buying some dowel jig bushings (like these, but not these, it was years ago so not sure on the specific version
https://www.amazon.com/Task-Pro-Center-07206TK-Doweling/dp/B00GNIGZRK) and used the drill press to drill holes at the angle and offset I needed in a block of wood and then pressed the down bushing into that and used it as a guide. For one-offs where I don't have a matching bushing I've just used a 2"+- thick piece of hardwood but that will wear and wiggle pretty quickly.. but for a dozen or so holes it works pretty well.
The forstner is a bit more of a trick though... because a down bushing or hole block of wood.. won't keep it from wiggling sideways. I could see a homemade jig made out of 4 blocks of wood, bottom block with a 1.5" through hole, top block with a "size of shaft" through hole, then a block in between them on either end to hold them apart a bit (probably just screwed together). Getting the initial angle on the holes just right would be tricky, but imho doable. Drill pilot holes, use a long bit/shaft to hold alignment and assemble then drill the two to-size holes. If you're doing a lot of angled the number of jigs could proliferate pretty fast (and the time spend on them as well).
