Walmart? Would not have guessed they sold 80/20. Here's a more typical site that thousands of engineers will use today to purchase extrusion for all kinds of industrial projects:

https://www.mcmaster.com/#structural-framing/=1dhfwat

Or, if you're a makerspace in the market for larger quantities and want to standardize, find a local vendor of extrusion (80/20, Misumi, Futura, MB Kit, etc) that will have the oddball fittings you may need on hand locally.

It's true that 80/20 will not sell you their dies, but they are happy to give away free CAD libraries of all their parts. There are subtle differences between different manufacturers, but everyone makes parts that are compatible with it and you probably shouldn't depend on the tiny features that won't match. It looks like OpenGrid saw a proliferation of too many 'standards' that were not open-source, and thought "We'll make a new standard that will be better than the others because it's open", and ended up adding a worse (less strong, less adjustable) standard product with limited adoption.

On the electrical boxes, they seem to be proud of their homemade enclosures. What they probably don't realize is that you can buy an IP67, hinged, IEC-rated enclosure with continuously welded seams from Saginaw or Hoffman with built-in grounding lugs, backplane, and latches for $80.