Which non penetrating method is recommended to check chicken breasts for done-ness when pan fried
There isn't one.

The only reliable way to determine doneness of a chicken breast is to use a thermometer. If you didn't have a thermometer then you would have to cut open the breast to confirm. Outside of those the only other method is experience. e.g. knowing that it takes 5 minutes per side to cook a breast of X size, in Y pan, on Z stove, at M heat.

Given that you own a thermometer, it's kind of silly to ask for another way. Use it.