As things stand, we at OpenGamma have heard no specific demand for Loans (as per FpML). We are more focussed on derivatives. However, Strata is intended to be a collection of useful asset classes, and if it is in FpML then that is a good guide as to whether it could be considered for Strata.
Personally, I think its great that you are considering adding the a asset class like this. But as an OpenGamma employee, I have to be aware that there is a cost to OpenGamma of integrating your code with no immediate benefit to the business. Ultimately, this is your choice. You can write the code in public or in private based on Strata. If done in public, you can do so by forking Strata or you could just create a separate project that depends on Strata. If it is public, then both you and us can see if it gains adoption, and at that point we could consider bringing it into Strata. If you do decide to do it in public then I can provide some advice on what needs doing.
Hope that helps, even if it might not be exactly what you were expecting.