So, I found out that if I go into the Cloud Save Data menu in my Switch's system settings, it lists every piece of software I've ever had on the system, including demos. I apparently forgot about quite a few of them.
ARMS/Global TestpunchBoo Destroyer will hate me forever for this, but even though I downloaded both the original Global Testpunch, as well as the regular ARMS demo, I never even started either of them up, and eventually deleted them.
Yoshi's Crafted WorldI talked about this a long time ago, but I was initially interested in this one, but actually lost interest after playing the demo.
Trails of Cold Steel IIII tried this just to see if I still felt the same about the Trails series (and also to see how it ran on Switch). I spent most of the time mashing through cutscenes, and never finished it.
Kirby and the Forgotten LandI felt about the same about Forgotten Land as I do most Kirby games. It's cute and fun, but I generally don't feel compelled to keep playing.
Lonely Mountains: DownhillA physics-based indie game where you ride a bike down a mountain. It was a little
too physics-based for my taste.
Blue Reflection: Second LightGave this a try. It's another game that feels like a visual novel trying to disguise itself as an RPG. The premise was intriguing, but I didn't finish it
Ys IX: Monstrum NoxObviously, this was just a way to try a game I was going to buy anyway.
Touken Ranbu WarriorsThis was a pathetic demo. All it was was a shallow tutorial that could be finished in about 15 minutes. It gave me very little idea of what the full game would actually be like.
New Super Lucky's TaleA cute 3D platform game originally for the Xbox One. Actually pretty fun, but I'm not big on 3D platform games.
Shining Resonance RefrainI talked about this a long time ago. IIRC, it was OK, but didn't hook me.
Fire Emblem Warriors: Three HopesI talked about this very recently. It's a rare instance where a demo made me reconsider a game I didn't intend to buy.
Project Octopath TravelerTried the early version of this when the devs were taking feedback. It was OK, but I'm not a big fan of the so-called "2D HD" visuals.
Trials of ManaI previously said this felt like a slow Ys game, but I still enjoyed it. I've since still considered getting the full version, but I always have other things to play.
Balan WonderworldYes, the infamous Balan Wonderworld. I liked the style and idea of it, but it was so oddly slow for a Yuji Naka game. I've heard the final version is a bit faster. It seems that the game was victim to behind-the-scenes drama, which is unfortunate, but it seems to have gained a cult following anyway.
Labyrinth of Refrain: Coven of DuskI'd completely forgotten about this one. It's a first-person dungeon crawler. I don't remember much else about it.
Monster Hunter Stories 2: Wings of RuinThe other Monster Hunter game I tried. Didn't hook me.
Disaster Report 4: Summer MemoriesWhen I first tried this, even I was put off by how badly it ran. I recently gave it another chance to see if it was as bad as I remember. It was. But I'm still intrigued enough by the game, itself, that I'm reconsidering it anyway.
Big Brain Academy: Brain vs. BrainThis was my first time trying this series. It was OK. Just seems like a more cerebral WarioWare.
Final Fantasy Crystal Chronicles: Remastered Edition LiteThis is one of those demos where you can technically play through the full game if you play online with someone who owns the full version. Again, this was just a way for me to start playing a game I intended to buy anyway.
Mario Tennis Aces: Special Online DemoI tried this twice, but it just felt too complicated for a tennis game to me.
Mario Strikers: Battle League First KickFelt similar to this as Mario Tennis Aces. You would think a Mario sports game would be more "pick up and play."
Daemon X Machina Prototype MissionsI remember being intrigued with this, even though it was a bit repetitive, but then kinda forgot about it.
BlazBlue Cross Tag BattleA button-mashy crossover fighter. It was OK, but I'm mostly not familiar with the properties represented.
Bravely Default II Demo VersionAll I remember about this is that the demo was really hard for some reason. I don't even think I finished it.
R-Type Dimensions EXA simple demo for R-Type. I bought the full game.
Stardew ValleyThis was a free game trial. Unlike the Story of Seasons demo I previously tried, I enjoyed this one quite a bit! I ended up buying the full game, partly because I wanted something to play while I wait for Xenoblade Chronicles 3.
Phew! I think that about covers it!