So to elaborate, there's no way to test the resistance against anything quantum computing capable, due to technology not being there yet? So as of right now, this quantum resistance is theoretical if I read that correctly?
Not exactly. We already know what is susceptible: RSA, ECDSA etc. We know that the digital signature scheme backing bitcoin and ethereum etc are vulnerable.
There are several classes of 'quantum safe' signatures of which hash based signatures used in the QRL are the most promising.
Based upon existing mathematics if a sufficiently powerful quantum computer were created by a government then bitcoin (and everything else) would insecure but the QRL would not. But you are right that it is of course theoretical resistance because no such computer exists publicly to attack either chain and test out the hypothesis!
The idea with the QRL is to get crypto ready for this computer advance so we are ahead of the curve.