What a thorough post.
Thank you for being thoughtful enough to tic a lot of boxes.

My experience is also Cervical fusion 3-4 through 6-7.
Apparently I had a degenerative disc condition, and in my youth played every contact sport I could. In full disclosure, played one final season of hockey after recovering from a 3 level Cervical fusion. Wasn't the same for sure, but I also allowed a few years to really let the fusion set and kept up with my PT and stretches daily.
Ultimately, the recovery time wasn't worth it (plus the cold nature of the playing surface and locker rooms aggravated the hardware, I believe. Rain and cold seem to bring on the discomfort), but was pretty happy with the fusions until about the 15 year mark.
Then started having ever increasing pain.
4th cervical level got fused (Dr. said fusing something meant to flex put undue stress on the vertebrae next to it), and almost literally a year to the day, was rear ended at a stop light.
Fast forward to '24 and thoracic spine is driving me nuts.
Thinking it's the degenerative disc issue, I see the surgeon again.
The look on his face when he walked in made me expect a Cancer diagnosis.
He said I had an advanced case of DISH syndrome, which is the calcification of soft tissue in the spine and where the ribcage and spine connect.
He also says Ankylosing Spondylitis, a cheery condition where my spine produces spurs that bite and pinch into nerves when I turn or move wrong.
When I ask what we do, he informs me they are autoimmune conditions with no cure and trying to keep range of motion for as long as I can is all I can hope for.

Oh neglected to mention I was 30 at my first fusions and told I had the spine of a 50 -60 year old.

I'm 53 now. Even if thoracic surgery for my spine became necessary, my Dr. says it's so traumatic a recovery, I might be better sticking with the Devil I know.

Bad as it is though, I hear so many bad things about lumbar operations I'm glad I haven't had that come up yet.

I would say research the Dr. extensively. Be realistic about what you expect to get from the surgery, and keep in mind your commitment to your rehab therapy after it's first prescribed is important.

I still stretch my neck 30-45 minutes daily, and am trying to do the same for the rest of my torso as the thoracic is giving me fits.

The technologies are supposed to be a lot better, but nothing is 100%, and slacking in therapy after is only going to affect YOU.

Best of luck out there spine sufferers.

Not everyone gets that every day can feel like an epic campaign. But there are those out there who understand. You are not alone.