I doubt you will see a Declaration of Compliance for RID/Flight Over People Category (1,2,3,4) anytime soon, for any currently produced aircraft on the market. Highly doubtful for any aircraft no longer in production.
Instead, keep an eye out for aftermarket, add on modules that will soon be hitting the market. One of those, with its mfgr paperwork, plus any documentation you can provide on your aircraft (what you've done to make it compliant) should allow you to properly craft and submit a DoC for your bird.
Of course, this is still 2 years away...so it's way too soon to even start worrying about it. 2 years from now you very well may have a new drone that complies and has a DoC registered with the FAA