I live just west of Minot and ice fish/spear on Sak a lot.
East end (east of Van Hook) has had a ton of baitfish (smelt) the last 2-3 years. Walleye bite can be frustrating, you can mark them and watch them on camera, but tough to get a bite. Same with the pike, everything is fat and happy right now.
There is a ton of water to look at and cover. Navionics is a great map of the lake, water depths vary, but the structure is there. Most of the bays have 15-16″ in the back reaches, but get thinner as you go out to the main lake. Main lake has only had ice on it for 1.5 weeks so far and with currents and water level fluctuations, it can be sketchy on the main lake and out towards the mouth of bays.
With all that said, there are a ton of walleyes in Sak. The bite is mostly morning and evening with day fishing on the slow side. Tons of structure, being mobile is good, water clarity is great so you can scout spot on spot structure. Mid winter, I’ve had best luck on deeper sunken islands (25fow+).
There are huge pike in the system, and just about every other species as well. Salmon, catfish, rainbows, perch, white bass, goldeneye, etc… Never really know what your going to catch.
Garrison is a great little town to stay in. Not much snow so getting around and accessing the lake is easy. Sak is one of the few lakes you could put a little effort in getting to a spot and go the whole weekend without seeing another person.