While I think the sentiment of doing something like this is great. I don't believe it should be exposed to the client in any way beyond a small blurb on your site that you do this with your profits.
I can only see this hurting you on an interaction with a client. For a client that is not familiar with OSS, I can imagine the thought, "So you piece together a bunch of freely available software in order to accomplish this, then charge me for it?"
Overall, making the commitment to contributing to projects you use is great. It just isn't a thing that clients will probably care about.
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