Can a customer who has purchased a plan which includes 10 sessions view how many sessions they have remaining in their account on their personal member page?
The only way i know is seeing the sessions remaining on the booking page.
For this question you are better suited going through Wix Support or reading through the Wix bookings own support pages.
https://support.wix.com/en/article/contacting-wix-support
https://support.wix.com/en/wix-bookings/setting-up-wix-bookings
As for integrating it for member pages, you can already use Wix Members app to utilise the Wix apps integration.
https://support.wix.com/en/article/about-members-area
In this article you can learn all about the Members Area, including how to set it up and customize it. You can also learn how it works works with the Wix apps such as Wix Stores and Wix Bookings.