Jesus prayed to God on behalf of the disciples (especially the original disciples) for protection and sanctification. But Jesus also made a prayer to everyone who simply believed in Jesus.
The big thing that Jesus prayed on behalf of all believers of Jesus Christ is unity. Jesus prayed "that they all may be one", much like the Father, Son, and Holy Spirit (17:21). Jesus called for unity so "the world may believe that [the Father] sent [Jesus]" (17:21). Although sometimes the modern church can struggle to maintain unity (especially with race and the hot-topic nature of politics), when a church does foster unity (especially in differences of race, gender, favored sports team, and Smash Bros. main), it can be a wonder to be seen. Martin Luther King Jr. is one example of a church leader who helps foster unity across racial lines, and to this day, people use him as an example to demonstrate the power of Jesus in fostering unity.
In regards to unity, Jesus talks about how He can be one with the believer and give them glorification (17:22-23). Part of how Jesus unites believers is working within them to empower and transform their own heart. Finally, Jesus asks the Father that those the Father gave Jesus (AKA the believers) would "be with [Jesus]" so that they can "behold [His] glory" (17:24). Ultimately, unification would be made complete in heaven -- especially with all the believers sharing in God's glory.