I don't see where the OP is getting the idea that they aren't coming up with new IPs.
Arms, Game Builder Garage, Astral Chain, Ring Fit, Labo.
I mean, however many IPs do you want them to come up with every generation?? They already have a ton of different franchises to maintain and tons of spinoff franchises from those (mostly from Mario of course). In fact they have so many franchises, in addition to coming up with new ones every gen, that some fan favorites get ignored for far too long.
I think the amount of new IP they came out with this gen was perfectly fine. In terms of none of them being huge sellers, well, Ring Fit certainly was a huge game sitting at over 15 million now. Not every new game is going to be a huge seller. You can't exactly fault them for coming out with several new IP this gen and only one of them being a huge seller.
As far as them focusing on "sequels, remakes, remasters, and ports" as the OP claimed, well the rest of the industry does that much more than Nintendo! And the only reason you are saying that right now is because we are nearing the end of Switch's life so yes indeed the past year or so they are filling in the software lineup gaps with remakes/remasters/ports because all the big new games are next gen titles.
I fail to see where the problem is.