Same here. I've been on all the public betas on my iPhone X. The latest public beta downloaded and the install started. After the phone rebooted, the progress bar got to the right hand side, and stayed there. For 20 mins. This isn't normal.
A vol + / vol - / hold power button reboot was needed, which started the update process again.
The update has completed successfully now.
Note to self: remember to reboot the phone before doing a major SW update.
Just came here to say this. Indeed, this requires a forced reboot @bkaus and @johannnn.