@xdenneboom I also have an IKEA Ribba Frame 70x50 cm² with the same setup (Chinese controller board controls 24’’ LCD-Screen from an old TV). For Power Supply I use a 12 V DC external adaptor and a step down converter to get the 5V for the Pi from the 12V supply of the frame.
I reinforced the Frame on the top inside with a small latch, glued the glass in the frame to improve stability and took some wooden latches to mount the display on the original backplate (see picture).