Doesn't take much to run a wii game at 4k 60 fps.  A 1080 from almost 10 years ago could do it.  

Lol I’m such a noob with PC that I still have yet to get my setting configured to run Dolphin/P64 consistently at 60FPS/1440p. I guess maybe I mistake needing a powerful PC for knowing how to use your PC for gaming.

(Though at this point, I have solved like 99% of the performance issues (it was mostly just (a.) AMD struggling to run a specific emulator, and (b.) my mini-monitor’s refresh rate is capped at 60Hz. Thankfully my main monitor is 144Hz.)

The Gamecube had 8 gflops of GPU performance and the wii 12 Gflops, just about any system can emulate those visually. Powerpc emulation is harder and needs more CPU resources but my cheap Celeron laptop has a passmark CPU score of around 2000 same as Switch 2 and that seems to be where you can get most Gamecube games to run at full speed but not all, and a few wii games at full speed. I have a cheap tablet with 4500 passmark cpu score, the Steam Deck is 9000, the PS5 16000, a cheap X79 based PC around 12000, a X99 based PC perhaps tops out at around 20000, my budget gaming laptop is 14,000 etc. My Steam OS mini pc based on a Ryzen 5700u processor is about 18000 I think. This little Windows 11 mini pc that cost about £70 I am using now is about 6000. My point is Gamecube and wii emulation super easy nowadays on pretty humble and cheap hardware. Full speed wii u emulation is not that taxing and neither is Switch. It probably won't be long before we get web browsers running Gamecube and wii games.

I bought my copies of Mario Galaxy and Mario Galaxy 2 at the end of the wii's life and I think I paid £3 or £4 for one and £1-2 for the other. So as I have physical copies of the game I feel entitled to run it on emulators on other devices. I'm based in Europe.

Emulation can be confusing, not aways straightforward.  I had no issues running 1440p at 60 fps mario sunshine on integrated graphics, once I got the settings right.  

What emulator are you using?  Some work better than others.  

Only way the Super Mario Galaxy games come to NSO is if they are delisted. There's no way Nintendo would charge for them separately and have them in NSO.

Super Mario 3D All-Stars was a planned limited release from the beginning. N64 ending up added to NSO with Super Mario 64. Sunshine is coming to NSO eventually. 

GLideN64 on Project64. Always leads to a black screen— seems to be an issue with AMD & whatever runs GLideN64, from what I understand. Dolphin also is a nightmare in that it either works perfectly, or I’m spending an hour non-sto restarting my PC b/c NSMBWii keeps crashing with an immediate black screen upon opening. (Funnily enough, no other game has this issue. Only NSMBWii for whatever reason. Hmm… I’m sure there’s some explanation.)

I was happy to pay $70 for two of the best Wii games ever and getting to enjoy them in 4K on Switch 2.

OP not sure why you didn't realize they were ports before you bought them. Shouldn't be surprised, they were never marketed as anything but straight ports. Nothing wrong with ports of two of the best Mario games ever. The price is too high for sure, they should be more like $20 not $40 (or $35 paired up), but it's supply and demand and Galaxy 2 at least isn't otherwise available on Switch and most people don't still have Wii games so they are overcharging for ports which is entirely standard operating procedure for Nintendo unfortunately.

No reason to remaster them though, not every game needs to be remastered or remade and Galaxy graphics hold up great. Heck even Mario 64 graphics with higher res hold up great on 3D All-Stars, and it seemed like people complained endlessly about that not being a remaster/remake. It's nice to know it's the original experience (but with today's higher resolutions) and they didn't try to tinker with a couple of the best platformers of all time.

I have Galaxy on 3D All-Stars but I'll certainly be picking up Galaxy 2 eventually as that is probably my favorite Wii game so it's worth the $40 even though the price should be lower. And when you compare it to other old ports Nintendo has sold at full price on Switch (sometimes with small updates), this at least isn't nearly as bad as that.

These games were also $20 on the Wii U when they were less than a decade old.

Buy the Klonoa collection.  Not simple ports. Upgrades to two fantastic games .