I bought a Steam Deck just to support the most important thing that ever happened to Linux gaming, but mine has actually just been gathering dust. It's far too big to really be a handheld, doesn't fit in my pocket, and does not fill the role that Nintendo's handhelds served for me. The main thing I do end up using it for is taking Deck + dock to FGC events for a portable setup.
Last year I bought a Miyoo Mini Plus, a little emulator handheld, as an impulse buy because it was on sale super cheap. I ended up putting far more time into it than I ever did with the Deck.
Maybe the best library of all time, my DS collection is massive.
The one thing that's sad though is how many classics are unlikely to ever see a rerelease. Games that were designed around the hardware just won't be the same on any other platform.
Two years of content seems plenty reasonable. Especially when they said from the start that it would be two years. Games don't need infinite updates forever and ever and ever. Especially when it's not a live service being sustained by microtransactions.
It's an iterative series, each game building on the predecessor's mechanics, so there's not any one major twist. But there are a lot of little things that add up. The new movement techniques are great, Salmon Run has been significantly expanded, and just in general the QoL is night and day.
Also, the fact that Ink Armor, Sting Ray, and Main Power Up are not in the game might be the true biggest step forward. S3's meta is in a pretty good spot now.
Large parts? It's been a while since I played Octo Canyon, but I'm pretty sure the only thing that reappeared from Valley was the Octostomp boss, but it's a different fight anyway so not really.
It'll never happen, but I'd honestly prefer for S4 to move on from Splatfests and do something else entirely. They've run out of ideas, a lot of the themes feel like filler just to keep it going out of obligation. At this point I just see Splatfests as a weekend where they take away Ranked and make everyone play the worst game mode.
Boktai series: These games were so near and dear to my childhood, especially 2. Really though you want the Solar Sensor hardware for the full experience, but I love these games too much not to plug them anyway. Emulating them is worth it over not playing them at all. And for the third game, you'd have to pick between original hardware or the translation patch anyway.
Castlevania: Aria of Sorrow - It's Castlevania. Also play Circle of the Moon and Harmony of Dissonance, but Aria is by far the best of the GBA installments.
Golden Sun 1/2: These games were way ahead of their time for how they designed a combat system that encourages you to use all of your tools and not just click basic Attack as if you gotta hoard your MP for a rainy day. Fantastic puzzles too.
Mother 3: Surely you have already heard of this game and do not need me to tell you to go play it. Have you not played it by now? Why not? Well, okay, if you haven't played Earthbound first, go do so, then play this.
Rhythm Tengoku: A wonderful game about pressing the A button. Sometimes you press the d-pad too. Translation patch.
Summon Night: Swordcraft Story 1/2: If you've ever played the classic 2D Tales games, these are excellent spiritual successors to those. There's a third game that's JP-only, translation patch is being worked on but it's been stuck in development hell for years...
F-Zero GX - As far as pure racing goes, GX is perfection.
Kirby Air Ride - The actual racing mode is... mid, honestly. But City Trial? One of the most interesting and unique game modes ever conceived. Sad this game never got any kind of successor.