"Secured by @Polkadot - slap that everywhere. It matters." But how?

Gavin Wood already said in "Glass with Gav" that it's sad that those who build on Substrate and Polkadot don't have to pay tribute to Open-Source tech.

But how can we require such projects to display a "Secured by Polkadot" on their websites?

Do we have to make Substrate closed-source, charge the DOT for the license, and require the logo to be published?

There has to be a more collaborative approach that maintains our Web3 and open-source ethos. Does anyone here have an idea?