Pros will often do 20 or more hours of Z2 in a week. For very competitive cyclists, 12+. At more than 10 hours a week, it would be hard for me to predict the interference effect of the cycling vs. the lifting as you'd be producing a not insignificant amount of training stress, even at that low intensity.
Once you have a power meter and an estimated FTP, I can more accurately assess the impact the training stress that you're experiencing. As I mentioned, you can auto-upload your data from strava to intervals.icu and it will generate a chart like this for you:
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I'm sad to look at this and share because it shows how my fitness has fallen off since I moved to a new house and broke my routine of riding every day.
In PMC terms (from the book I mentioned) "fitness" is chronic training load, "fatigue" is acute training load, and "form" is the delta between them.
These concepts are hard to gain an understanding of, but represent the real value in using a power meter. It's less about riding at a particular power target, which you'll figure out how to do pretty quickly and less about bragging about your FTP and more about precisely accounting for training load and doing that thing we all know and love called "progressive overload".