Red Hat has an explicit clause in the contract allowing work on open source projects. As always best to consult a lawyer (not one connected to the company) if this is likely to be important to you.
Would you, or somebody working, or who had worked for Red Hat be willing to copy paste that clause, or contract, redacted of course so we could use it as an example.
Red Hat being who they are, their approach is extremely relevant to this situation.
I did try to dig out the contract just now to see if I had a digital copy of it, but I don't think I do. It's likely to be a two decade old printed copy instead. I think you need to talk to a lawyer rather than trying to do this on the cheap. Your lawyer has your interests at heart, no one else does. If you're a member of a union (Prospect being a good one for digital workers) then they will have lawyers you can consult for free.
I will talk to a lawyer as well... but I'm really interested to see something concrete too. I've asked many times but I've never actually received an example of what an actual contract had written on it.
