Then I realized the 100 hours material participation rule could be construed as active income and jeopardize my green card chance.

Take a hard look at your presentation and materials.

Have the materials failed (leaks)?

Issue a mandate to the PM that any repair over #XXX needs an Itemized Time & Materials Purchase Order to be completed by them and your signature of approval, without which the PO is denied. 

Certain materials better than others?

So, there will always be rehashing of the same material.

Lastly return and additional material you bought for a refund.

Granted they were purchased Dec 2021 (shortly before the rates started to climb).There is more education material available today than ever.  

really depends on which materials you're looking to go with .

So to say it improves returns in any way shape or form is materially untrue.