It's got a much bigger user base than Switch in the UK, so it would of been a bigger achievement if the Switch version outsold it. Although it was a difference of 250 copies so they practically sold a pretty even amount.
It'll come down to which version has the longest legs, which Switch has the bigger advantage in because of it's newer lower growing install base hasn't reached anywhere near it's endpoint yet.
I'm guessing that these numbers won't include digital as well?
As time goes on I'm buying less and less physical games for my Switch and gravitating to digital. That's just me but I wouldn't be surprised if it was a trend shared by other Switch owners.
It's true that the Xbox will have a chunk of it's sales via digital as well but I feel that the nature of the Switch lends itself to digital more than a dedicated home console - less things to carry about and potentially misplace...
Will be interesting if we get publisher numbers at some point that includes all sales. (again, assuming they're not included in these numbers).