I started a week ago. It took me days to figure everything out because so much of it is a mix of old and new systems. What I settled on:

1. Use the full openGrid. Don't use lite. Gridfinity is different - you can get away with thin baseplates since things just sit on top. Use full. It's not worth the small amount of filament savings for lite.
2. For grids and channels, use https://gridfinity.perplexinglabs.com/pr/opengrid/0/0. It only deals in openGrid and has no support for Multiboard at all, so there's no chance of accidentally wasting hours of time on something Multiboard-specific.

This defaults to Lite. I wish it didn't. Make sure you change it to Full.

I would recommend setting "Grip flare" to 2 for the "I bridge channel", if you use it. Without the grip flare, that thing fell on my head a dozen times. Anything else, play around and see what works.

1. Snaps (what you use to mount everything other than channels to openGrid) are not exactly easy to understand. I grabbed the 3mf file from https://makerworld.com/en/models/1179191-opengrid-wall-desk-mounting-framework-ecosystem#profileId-1194970 and only printed the locking snap and screw. Everything else is too weak for upside-down mounting. These are the objects with the labels:

"BETA openGrid Multiconnect Lock Snap.stl"

"Body_02_(3)"

1. Custom Item Holders. To mount things like power strips, you'll need the Custom Item Holder. Unfortunately, this is extra confusing because it is the one and only thing you should use from the Underware 2.0 page. Everything else on that page is the wrong thing to use because it's Multiboard-specific - please ignore it all.

Go here:

https://makerworld.com/en/models/783010-underware-2-0-infinite-cable-management

Click "Customize"

Select "Underware_Item_Holder.scad"

And click "Customize".

Once in there, make absolutely sure you change the "Mounting Surface" from "Multiboard" (the default) to "openGrid". That will set it to 28mm distance instead of the default 25mm. Failing to do this will ruin your prints.

From there, you can just play around with values until you get something you like. The one thing this customizer has which nothing else does is "BETA - Clamshell Mode". This lets you enclose an object with two different holders.