AFAIU the Debian i386 port has effectively required i686 level CPU's for quite a long time (CMOV etc.)? So if he has an older CPU like the Pentium it might not work?

But otherwise, yes, Debian 12 should work fine as you say. Not so long ago I installed it on an old Pentium M laptop I had lying around. Did take some tweaking, turned out that the wifi card didn't support WPA2/3 mixed mode which I had configured on my AP, so I had to downgrade security for the experiment. But video was hopeless, it couldn't even play 144p videos on youtube without stuttering. Maybe the video card (some Intel thing, used the i915 driver) didn't have HW decoding for whatever video encoder youtube uses nowadays (AV1?), or whatever.