Lineage 23.0 (Android 16) has been released for the Pro1X. I haven't yet had time to install it bbut will either tonight or tomorrow morning, if you want to let me be the guinea Pig. 😉
https://download.lineageos.org/devices/pro1x/builds
https://wiki.lineageos.org/devices/pro1x/upgrade/
https://wiki.lineageos.org/gapps/
Lineage-23.0-20251013-NIGHTLY-pro1x with October 1st security patch installed smoothly using the Lineage upgrade procedure linked in the OP. It was installed with MindtheGapps 16 and Magisk 29 installed as a zip for SU only. all data was preserved in the upgrade. I did have to open the Magisk app to let it run an update, but root was established. All went according to plan and everything seems to be working so far.