Indications were that Super Mario Wonder had not been hitting pre-order expectations in the UK. One of the big retailers actually offered it at 25% off for pre-order and it was massively advertised(I was getting targeted with it on sites like Metacritic) so likely it had been hugely overstocked. The week 1 sales were 62% down on Tears of the Kingdom, but I think it would have been crazy stocking it based on similar expectations.

If the ratio to Zelda holds out worldwide it will sell around 4m, which is not bad at all I think.

Chris Ding clarified that it is common for the PS releases to be quite more frontloaded and Ninty long legged to the point it is normal for PS to take the first week crow while Ninty will get the overall highest selling. He also pointed to the fact it is 2D mario and there have been plenty of Mario games available on Switch while SM2 is basically the first PS 1st party in the year and even regarding exclusives there weren't many.

Not a surprise really. Most predicted this will happen, especially in the UK. Spider Man will most likely have a better launch WW as well. The question is will it stay that way by the end of the year and the answer is no. Mario will outsell Spidey during the holidays. Launch - Spider Man, Short term - Mario, Lifetime - ???

Most likely lifetime will go to Spider man if we assume that it will be ported to PC and go through multiple price cuts. That's something Mario Wonder won't have, however it could be close depending on Nintendo's next console.

Seriously though, a lot of kids will still be gifted SMBW for Christmas, but 2D Mario also isn't the automatic bazillion seller some people think it is.

Not a major surprise, UK tbh is one of the weaker countries for Nintendo, it wasn't until very recently the Switch outsold the Xbox One over there which is wild to say since it felt like an eternity since the Switch outsold the Xbox One globally.
Also, I definitely feel like Mario Wonder isn't the type of game to necessarily have huge launch numbers, I see it as more of an evergreen title since simpler Mario games don't have as much of a harcore fanbase like bigger more complex games like Zelda or even Spiderman, I see the Mario audience as being more casual gamers who would pick it up once they hear about it or get the opportunity, in the long run Mario Wonder I believe should do better overall.

I'm pretty sure Mario Maker 2 had a better launch period than NSMBU but NSMBU ended up outselling Mario Maker by more than 2 times as much just off of evergreen sales alone.

In terms of other sales stats, the launch of Wonder is down 62% compared to Zelda in the UK. But again I expect Wonder to do better when it comes to evergreen sales.

Compared to NSMBWii, Wonder's launch physical sales are about the same in the opening period with 79,000 copiers sold. It's good to remember though this doesn't include digital sales of Wonder so if we were to assume the ratio stays the same with 50% physical sales and 50% digital sales, Wonder had a launch most likely that was twice as big as NSMBWii, which is impressive.

Also, in pretty much every country Mario Wonder is remaining the top video game seller in Amazon beating spiderman 2. I expect Wonder to fair much better worldwide than in the UK.

I would have been surprised if this wasn't the case. As someone who loves Mario and Spider-man, if I could only have bought one of the games day 1, it would have been Spider-man 2. Just because of the type of game it is.

The UK disappoints once again.

how big are file sizes for both games?

Great numbers for both. Spider-man 2 insanely high also considering the 45M Global userbase compared to Switch 130M. But we should also say that Mario Wonder will most probably have great legs, so I would say these two titles will do miracles for both Consoles ;)

SM2 is close to 90Gb, Mario is like 4Gb.