It's common knowledge. Switch is much closer in both power and architecture to PS4/Xbone than Wii was to PS3/360, this is why we see ports the kind of ports to Switch like Doom 2016, Hellblade, Wolfenstein II, etc while Wii never got those kind of conversions. As for them being profitable, they did it 5 times. Companies don't repeat unprofitable ventures.
For what it's worth, the Xbox 360 and Wii both had Power PC processors, and the PS3 used a Power PC-based processor. The Switch uses an ARM processor. Last I checked the Switch's ARM processor is nothing like the PS4 and Xbox One's x86 processor. Even if the Switch is "Closer to power and architecture" doesn't mean it's easier to port. And besides, even if it is easier, how much easier is it? Define "Much less investment".
Also, kinda curious how you appear to be pretending that two Call of Duty Wii U titles didn't exist. I wonder why... perhaps that has something to do the lack of an appearance of a Switch Call of Duty title? I bet it did.
But even assuming the Wii U had nothing to do with it, just because Activision invested in several Wii games doesn't mean they were happy with the sales of each of those titles, and we don't know whether the development of those titles was subsidized, or whether Activision was required to honor an agreement with Nintendo regardless of sales. There's a lot of politics involved in video games, and you're making several assumptions by just chalking that up to "companies don't make repeat unprofitable ventures".
Besides, didn't Nintendo just release another Labo kit? My local game store hilariously displayed them right next to the $9.99 clearance bin Labo 1 and 2 kits they had on display. Sony's still losing hundreds of millions of dollars a year churning out cell phones year after year too. Seems to me that companies repeat unprofitable ventures regularly.
PS3/360 had DX9 era GPUs and multi-core, multi-threaded 3GHz CPUs versus a DX7 era GPU and single core/single threaded 729MHz CPU on Wii, also 88MB of RAM vs just under 500MB. Switch's GPU is actually more modern than PS4/Xbone, it's CPU is also multicore just with less cores at not to dissimilar a speed, RAM is much closer at 3GB vs 5GB. The gap is objectively much smaller this time around.
Do you have any evidence that COD on Wii didn't make money? Cos the actual evidence, the fact they brought over 5 of them, 4 of which sold over a million, points to them being worthwhile.
For someone who claims to own a Switch you come across an awful lot like someone who hates Nintendo and wants to see them fail.