Pull Up bar holder for 20mm bar. There are two types, one with screw holes, other without. Can be attached to wall with strong double sided tape, or just screwed.

Bar slides in from top. Can be fixed with pin, so it doesn't rotate, although it sits tight enough.

Choose carefully where you mount it, because it can damage the wall - tiles for example.

Tested 70kg on just one side with double sided tape.