It's easy with basic woodworking tools!

Go look at high quality prehung doors and you'll see it's not much
more than three boards, two rabbets, and some mortising. You can
attach the stop strips after the door is hung.

This past winter, I made maple door frames for a commercial project
that came up with free maple doors with no jambs.

It seems easy. What seems a little difficult for me given my bench-top TS
is that most jamb thickness appears less than a 1-by. So, I might have to
somehow shave the thickness down, unless the rough opening is large enough.
And since the standard size is 4- 9/16", I'd have to rip down a 1x6 on the
TS, and somehow clean up the saw marks, I guess with a ROS.

Other than that, how hard can it be?