It’ll give you aerobic training, but it places very different stresses on the body (as you know!). What you won’t get is the stressing and strengthening of connective tissue and other effects of running. Because of this, when you return to running it would be a good idea to ease into it, esp. coming back from injury — maybe start with a walk-run progression. Are you being advised by a physio?

Those with greater knowledge might correct me, but as far as I understand your aerobic capacity is defined by the local muscles used in the activity of interest and not by the heart. The heart rate (and HR drift) is simply an effect of the work performed by the local muscles. Consequently, the aerobic capacity – and therefore HR drift and HR zones differs between different sports/activities. For myself, my aerobic capacity (upper Z2 HR ) is 137 bpm in running, 132 bpm in uphill walking on treadmill and 122 bpm on a bike.

As far as I know, it is common to have an AeT 10-15 bpm lower on the bike compared to running, unless it is a person who do a lot of bike training. So it might be an good idea to stay a little bit lower on intensity (heart rate) on the peloton compared to the running.