When I became hyper focused on my heart rate I could tell you what it was without checking and was never more than 1-2bpm off. I could be sitting in the car with my misses and say "85", and I would check and I'd be either right or only 1-2 bpm off. It's a serious problem if you let it become one.
I have friends that would post their fitbit results on exercise runs/cycles/whatever that they had done and it would show averages over 100bpm and peaks of 160-170bpm, and the very idea of deliberately doing that would fill me with dread. I had no idea how they could push themselves like that. Yet...I would have done exactly the same thing for decades before I had anxiety.
It's just perception of an issue rather than an actual issue.
Good luck in your move to Germany. Being alone there is an ideal opportunity to really take up and practice meditation