Fried sage leaves or crumbled cheese such as Cabreles blue?

Best of luck, I hope some of the more experienced cooks will have additional suggestions.

The fried sage leaves would be great--and maybe you could fry a bit of pancetta and chopped chestnut and crumble them both on atop along with the leaves. Something bright green, like chopped chives or parsley, would look good, just because of the color contrast, but you don’t want too much going on!

Buttered breadcrumbs and pecans.

Risotto isn't much of a garnish/accompaniment "kind of dish"; it stands alone. A few shavings of parmigiano or pecorino (maybe even asiago) is all that is necessary.
The only other thing I can think of as a garnish that wouldn't distract from the flavors you already have is a fried brunoise of butternut squash. Maybe toss them with a touch of aged balsamic straight out of the fryer/oil. This would serve as textural and acidic component.
Or a tiny salad of microgreens or baby arugula; for color and some freshness. Bull's blood would look awesome, but they're not that easy to come by (especially just for a garnish).
Just nail the risotto and don't over-complicate it and you'll be fine; garnish or not.

Good luck by the way!