Builder centric Multi Vendor Marketplace

Hello,
I am a very interested in setting up an Upfront Builder centric Multi Vendor Marketplace.

I have built multi-vendor marketplace featuring woo-commerce before for a well-known author/illustrator. The marketplace will be running on a well specced Droplet on DigitalOcean.

I will also be providing a WPMU "sandbox" featuring Pro Sites and Upfront for the Vendors who join my marketplace to take advantage of.

I want to pay proper attribution to WPMU Dev as much as I can without coming across like I am an affiliate because as we all know WPMU Dev does not do affiliate programs.

To be clear, we will sell Upfront builder themes ONLY on this marketplace NO other themes whatsoever. Making it completely bespoke, which is why I am concerned about any potential infringements I may inadvertently make and how to properly credit and attribute WPMU Dev.

My specific questions?

Theme attribution: I would like to know what is WPMU Dev preferred method of attribution for the boilerplate that will end up on each theme on the marketplace?

Is there any specific messaging required to serve as a global attribution to WPMU Dev?

Do purchasers of the themes need a WPMU Dev account?

Are there any Upfront or WPMU Dev icons or images we are allowed to use in our descriptions?

Anything I missed I should know?

Thank you very much in advance for helping clarify this for me.

I've learned so much from my membership here. I really appreciate this community and I have a feeling there will be no shortage of WPMU Dev members looking for a nice marketplace to sell there new creations.

Selling on theme forest is one thing, but a completely bespoke marketplace I think would be a great boon to the Upfront Builder creators.

Kindly, Matt