Pumping question

This may sound stupid but does pumping (or PE in general) affect the inner penis as well?

If you pump at low pressure for a long time, you definitely get tunica expansion.

No i mean the inner inner penis. Like starting from the pubic bone to the bulb where the BC muscle is

Yes

Your base girth gets the most expansion so you are getting expansion beneath your fat pad, but I don’t know how deep into your body that expansion reaches. I wouldn’t be surprised if the stimulation goes an inch or two inside your body.