I doubt that they have 28M Series sold to consumers; maybe shipped. I think the most credible number we have at the moment is from Take2's Q3 report where they said what is the total next gen install base and from that, by subtracting Sony's official number, we got something like 25M (at most) Xbox consoles sold through by the end of 2023.
I think that they'll reach 40M sold (still a horrible number and a big drop from Xbox One) by the end of the gen but of course I base this on MS's own internal documents that have next gen planned for 2027/2028.
2026 is not happening and I'm frankly shocked how this date has got any traction and wanna know where it originated from.