I totally forgot that the Switch 1 didn't get any Call of Duty games. If I recall, there's a deal between Microsoft and Nintendo to bring that franchise to Nintendo platforms in the future. I think we'll see a couple come to the Switch 2 if this is true. 

Does anyone have the answer to these two questions?

1) What is the most GTA5 sold on a single console?
2) How many Switch games sold more than this amount?

On a single console, the only information I can find is on Wikipedia where it's based from April 2018 where GTA 5 had sold 90 million units by that point, and the PS3 version had 32.8% of that figure, which equated to 29 million copies.

Whether that's accurate or not, I can't find a way to verify that. But a lot of sales are from double, if not triple, dipping on other platforms. 

Either way, the Switch had 5 games that surpassed that figure.

Counterpoint: Wii Sports & Zelda BotW.

Those were launch titles to get initial interest in the console. Every console has one. Wii Sports actually should have an asterisk due it being a tech demo that came bundled for free to the overwhelming majority of Wii buyers.

Both consoles had a quite a few insanely high selling games that helped defined them throughout their run. BotW alone barely makes it into the top 5 of best selling Switch games. 

Even if Wii Sports and Zelda BotW didn't launch on those consoles, they still would've been fine thanks to the plethora of other major releases. Same thing if Switch 2 doesn't get GTA6. The console will be just fine.

Now if Wii Sports and BotW were the ONLY games on both consoles that sold anything and everything else was a flop, that would certainly be a different story lol

I point to Wii U as a shining example of a system with a plethora of major releases that was killed mostly due to having a terrible start. Nintendo was pulling up with the best games of 2014, even amidst the PS4 first-party drought, yet sold no more than 3.5mil Wii U systems. That said, I do firmly believe that had Nintendo not launched Switch with a system seller like BotW, being that consumer confidence was already very low in Nintendo, I don’t think the system would’ve seen anywhere near the same level of successful. Similarly, had the Wii not gotten Wii Sports, the casual would’ve never been attracted, and the non-casual would’ve flocked to PS3/360 (as they had during the prior generation).

You kinda just proved my point though that a single game doesn't make or break a console. The Wii U failed not because it didn't have a major game, because it had several notable sellers, but because of Nintendo's inability to market it properly to the point pretty much no one knew what it was and focused on hardware gimmicks that didn't resonate. I thought it was another attempt at a Sega 32X/CD or something lol let alone it being Nintendo's next-gen console. With the Switch, while consumer confidence was certainly low, not only was Nintendo clear and concise with its marketing as to what the Switch was, it had more than just BotW throughout that first year. Immediately after launch the Switch had MK8D (which has more than doubled BotW sales) Splatoon 2, Mario + Rabbids, Xenoblade Chronicles 2, and Super Mario Odyssey for its Holiday season (also right there with BotW in sales) to top it all off.

Sure it may not have immediately had the atmospheric success those initial first couple of months, but there's no way the Switch would've floundered. Console sales typically increase with time after the first couple of years, and with how consistent Nintendo has been throughout the Switch's life, it definitely would've had very similar results in the end.

The Wii though, yeah you may be on to something there. Although the Wii was not sold bundled with Wii Sports in Japan, and the console was still a great success in that region, so it's hard to quantify. But the Wii still had some major system sellers such as Mario Kart Wii, New Super Mario Bros Wii, Smash Bros Brawl, or Super Mario Galaxy. The first 2 selling well over 30 million units each. I will admit, the Wii may not have reached the 100 million mark, but I highly doubt not having Wii Sports would've "broken" the console.

Ironically, both the Wii and Wii U had the likes of CoD on those systems, and yet they both had extremely different results which continues my original point.

This should make it pretty clear why Nintendo doesn't "need" GTA on its platforms.  GTA5 has sold an amazing amount, and it it usually the top selling game on whatever console it appears.  In spite of that Switch has 5 games that surpassed what it has sold on a single console.  Nintendo makes its own high selling games, so it doesn't need big third party games like GTA.

I genuinely believe that we are far removed from the days where ANY game has that kind of influence anymore. No, Switch 2 or any console does not "need" GTA6.

Definitely. And seeing the exact same blackhole live service games being the most played every month on all platforms just shows that people are just gonna play where they want to play.

And with Nintendo FINALLY carrying over digital libraries, saves, etc from the Switch to Switch 2 with a Nintendo account, just means now more people will dig themselves into that ecosystem the same way Xbox and PlayStation playerbase did throughout the 8th generation with very little leeway.