Replace garage door windows

(I keep getting AI suggestions that my post is in violation...)

Our long panel windows frames are in rough shape. The inserts are in great shape, as are the interior frames. They are CHI brand and they don't sell parts to the public. I want to make some external frames since I can't find anything off the shelf that is the right size.

Any opinions on using plastic or vinyl trim to make a frame? I would use adhesive to bond the corner cuts.