Right, so I do a 5/3/1 with a circuit of assistance work with essentially no downtime apart from switching out the weights. It's challenging, and it builds my strength, but I don't think anyone with any serious amount of experience doing cardio-focused exercise could with a straight face say that they are comparable. High zone 2/low zone 3 maybe, but not comparable in volume to a long run/ride nor comparable to HIIT sessions either.

If lifting weights is seriously that taxing for you cardio-wise, you may need to get out and actually stress your cardiovascular system