Gaming consoles typically take 3-4 years to finalize and another year to get to market. So if an XBOX handheld is to come in 2025 it can/might be announced at the Game Awards in two months. Otherwise, it'll be 2026.
As to the portable OG XBOX, no question getting a functional XBOX and Duke controller into a mobile form factor is quite an achievement.
But...
...since he used an original XBOX motherboard...
...unless he got really inventive...
...the thing needs an optical drive (real or virtual) to do anything other than boot up.
Real might allow actual gaming from commercial disks. yay!
Virtual, though...
A similar project based on the Valhalla 360 would be a good followup.
More challenging, though, since the architecture is proprietary, not a disguised Celeron+Nvidia PC.