The Japanese support in Japan specifically has been very poor this gen and I don't think Tango is going to change that. A lot of Japanese devs don't even release the Xbox sku over there on multiplat games.
The Series X+S will likely sell less than X1 in Japan over all. Selling out a low stock shipment for launch day on Amazon Japan won't change much and Gamepass for Japanese heavy hitters like KH, FF or DQ comes years after the initial Japanese release. I would be very surprised if they even sell 75k there for the Series family when it's all said and done. That's not progress.
If PS5 sales remain flat or even decline relative to PS4 and Xbox Series sales somehow to remain on par with Xbox One, then yes it’s a minuscule marketshare gain. Cmon I was joking here saying 1-2% gen over gen gain. Absolute peanuts and even that somehow seems unacceptable. O well