I threw some BMX bars on a mountain bike that previously had old school super long stem and straight bars. Did it more for goofing around and to have a giant BMX bike, but actually put some miles on it cruising around and it's not bad at all.

Threadless BMX stems are standard 1-1/8" steerer tube clamp, so no problem there. BMX stems and bars are generally 22.2mm, or 7/8ths clamp diameter. Although I think some 25.4mm stuff is floating around now. You will likely need a new 22.2mm stem to match whatever bars you get, if only because you need some serious BMX stem clamping action to keep 10" tall bars from tipping forward or back.

Also they are available is almost any rise from 5" to 11" or so. Dans comp is the gold standard of online BMX shops: https://www.danscomp.com/