Convert Apple Maps coordinates in universal format

I would like to convert the coordinates displayed in Apple Maps as

38,89016° N, 1,22427° O

(German notation)

or

38.89016° N, 1.22427° E

(English notation)

into something like

38.89016, 1.22427

(Expected result)

but only if the user did enter a expression matching this pattern and not if the user enters something like an address or anything in the input field.

Therefore I would be using PHP preg_replace()

However I have difficulties building a matching regex and was wondering if someone found a solution to this already?

I already tried different regex variations on my own already, but they did not work anything like what I would expect, so I did not add them here.

I though have a regex to verify, the expected result is in the correct form which does work as expected, though I wasn’t able to modify it for the replacement:

/^[-+]?([1-8]?d(.d+)?|90(.0+)?),s*[-+]?(180(.0+)?|((1[0-7]d)|([1-9]?d))(.d+)?)$/