That business model exists and appears here periodically complaining about how unfair Microsoft is. We don't care, we'll meet Microsoft where they are and just offer their customers a more specific solution.

Then make this specific solution open source, and make the laywers pay for support and roadmap decisions / features they require! Make them pay for integrations with Azure AD and struff like this! Make them pay for the binary! The possibilities are endless, it can work!

You can aim for better than "where MS is".

This could constitute a killer argument to make your solution appealing.