For adding any custom tab to the BuddyPress you need only to use simple addons for the BuddyPress which you can install from the WordPress site.
Some Addons are:
Can I Create Custom Tabs On BuddyPress?
Update on March 17, 2020
For adding any custom tab to the BuddyPress you need only to use simple addons for the BuddyPress which you can install from the WordPress site.
Some Addons are: