thanks for your replies.
yeah. very tricky. Is the GPS really worth mentioning? because in normal office environment only Intel graphics is activated.
Before thist test, I have tried HP Elitebook with AMD cpu and graphics, as well as a Full HD display with 1000nits - it gave me some mild eyestrain. After that I've tested the mentionend Lenovo, which was "ok" for the eyes. Due to I haven't liked the overall quality and performance of the Lenovo, I have bought the HP, which gives me terrible eyestrain. I know that the Lenovo is color calibrated and the HP not. However Notebookchecks said, that the overall performance of the HP is much better, although the same components.
I also want to check if I could get used to the HP, however I thought that my symptons have gone better, this test teached me the opposite.