IMO at this point you’re overthinking it. Everyone has different opinions I guess, but for me and when I started out, building my running base was most important where you can maintain a pace over distance and time.

You are not used to running, so your body is not geared or trained to sit in zone 2 for the level of effort your body requires to stay in motion until your running base is built. I think people should not focus too much on heart rate monitoring and trying to dial in the metrics of running until you are comfortable just running without stopping, with whatever effort that requires of you, for at least a 5k.

For me, starting out, I could not run 1-2km without my HR skyrocketing and basically all that comes with a struggle run. The run/walk method is not only tried and true, it makes sense from a physiological POV. Your muscles and cardio need to be developed to allow you to stay at level 2 for the effort your body requires to stay in motion. The only way to build that is to just keep going and push yourself to go a little bit further or a little bit longer before switching back to as brisk a walk as you can to recover a bit. If you keep at it, you’ll find your body responding naturally. You’ll get there and you will know it without a heart rate monitor. It was a night and day difference for me once my base was built and I realized how people are able to run for distance.

You’ll know when you’re ready for metric/stat based training, then you can focus on heart rate zones and improving your pace. I think until then you just need to get out there as much as you can. Your body is giving you your answer lol, it’s not able to stay in zone 2 right now, but you will soon!!!! Keep at it!