a good start, agreed that you have a lot to peruse. Like the purely visual, also agreed that the thumbnails on-click should be bigger.
Some suggestions, apologies if they are already there and I missed them:
Molded plastics joining including threaded inserts, studs, heat staking, ultrasonic welding, chemical welding.
T-slot extrusions with various T-nuts i.e. Bosch, 8020.
Welding as an entire category seems missing other than generic laser welding
Self adhesive parts, labels, windows.
There’s an entire world of tensioned fabric design with myriad joining mechanisms, some of which are alluded to.
Quick-connects i.e. slip-ring ball-detents used on high pressure hoses
Chemical fittings such as luer and other bayonet or high-helix turn fasteners.
Keep it going, it’s a worthwhile effort.