My friend and I wanted to do a speedrun but we don't know how to time it, anyone knows?

Use a timer. An example could be livesplit which is downloadable on a windows laptop/pc. The timer does not need to be on screen.

Use your phone's Timer

Alternatively, you can also not time it, and we will retime it for you.

Is it possible to make recording longer than 10 minutes on xbox

you can livestream instead of recording

Is it possible to make recording longer than 10 minutes on xbox

How do i get access to the stream after im done?

There's something like a browser on PS4.