I'm streaming those new NSO additions for NES, SNES, and Game Boy if you want to see them in action.
Edit: Here's the archive.
Mystery Tower (NES) is a solid puzzle game that takes a bit to get the hang of its techniques, so check out that strategy wiki walkthrough that explains the mechanics pretty well and has a guide if you're getting stumped on a stage. This is a good game for the rewind and save states to undo mistakes as you figure it out.
Master Blaster: Enemy Below is fine, though I've not played any of the other games in the series to help me know if this GB game is a solid adaptation of the original games' mechanics. It can get frustrating just wandering around areas and having enemies respawn so much to wear your health down very quickly in some areas.
Kirby Tilt 'n' Tumble is a great Kirby spinoff. They adapt the motion controls of the original game to the Switch's gyro, so it works pretty well. This is another game where the rewind makes it easy to undo mistakes and bad play to be a bit more enjoyable.
Harvest Moon seems neat for what it is, though this is obviously the first game in the series and is a bit rough around the edges. Many of the later games in the series and various other games influenced by it are probably more accessible for people like me that never played this.