It is not a too ore deal to refocus a SG9665GC, i did so with my first camera, and really the only parts you had to keep just a little eye on taking it apart was the "click" mechanism for the adjustment up and down of the lens.
when you have it apart and the lens loose it just take a few degrees from its current position to get back into focus, so be sure to mark the lens in the position it are in before you loosen the lens.
Then when you have done that changed the lens ( i think you probably have to screw the lens in a bit more ) then make a test recording with the camera still apart by powering it from a power bank or a mains USB charger for something.
then preview your recording on a PC or maybe a TV, something with a large screen so you can best see the focus.
You probably have to repeat this a few times before you have found the sweet spot for the focus again, but this should not take more than 10 - 15 minutes of trial and error.
When done secure the lens in place again,,,,, do not use CA glue,,,,, i have some times used regular wood glue and once a clear varnish normally used for tying your own flies for fly fishing.
If you have not removed too much of the locking glue from the factory install and the lens still are tight to unscrew or screw in chance are you probably don't need to use anything to lock the lens in place..
You can find many videos on youtube about how to change lens on action cameras, the procedure are much the same on a dashcam, just the housing are different but the lens and so on are the same 12 mm fine thread lens.