I don't think it matters much. Since you're making your own highway pegs, you can customize how they mount and where. You can adapt them to whatever skid plate you like, or modify the skid plate to fit pegs, or some of both.

I didn't have much trouble adapting the Happy Trails bar to my Enduro Guardian skid plate. All I had to do was drill one extra hole in the peg bar, so that there were 2 holes that lined up with existing holes in the skid plate. Then used fender washers (because the holes in the skid plate were pretty big), bolts, and nuts to mount bar to plate. Can post a photo if that's not clear.

Drilling your own mounting holes in whatever skid plate you have is particularly easy when it's aluminum. I believe the Givi skid plate is aluminum, and pretty thin at that, so probably the easiest to modify.

The problem with these bars is that they are very strong. If you go down, one end will dig in, and the bar will twist your skid plate.

The Enduro Guardian footpegs solved this problem by making the pivot point very close to the skid plate and the flip up footpeg part as long as possible (so it could still fold up without contacting anything). That way, if you go down they fold up and can't dig into the ground or hit anything when they fold up.

I've dropped my bike several times with the EG skid plate and footpegs and never had any problem with either.

The part that accommodates your foot is probably less than half of the length that folds up.