There's a dealer in Texas (Hurst) that's installing 2.5 and 4 inch Ready Lift kits on 2021 Tahoes and Suburbans right now, with both kits they are running 35s. I have no clue how much cutting (if any) they are doing, but dang to they look good. Hopefully this is a sign of things to come.
I reached out to Readylift as they have liked a number of the dealer's posts on Instagram asking if the kits they say they are using are coming to market soon, and I got the following respsone:
"We have not yet been able to test or release a kit for that application so at this time we cannot confirm fitment or tire sizes that are able to be ran. We are hoping to have something released in the next 3-4 months for that vehicle."
Maybe Hurst is repurposing other kits somehow? Regardless, their Tahoes and Suburbans look great!