Yuriy, this looks useful and I’ll take a look at these for my own startup, but one point of clarification that you guys might want to double check with a lawyer: not having a license does not mean that anyone can use it, it means that no one can use it. Licenses aren’t restrictions, they are grants. Without a grant, no one is allowed to do anything with them by default.

You very likely need a license so your customers aren’t (technically) in violation. CC0 license is a straightforward one for these kind of situations, might be worth checking out.

Per usual: not a lawyer, certainly not your lawyer, please double check with an attorney.