At least here in germany we use Cat.7 in general since, it feels like forever, at least in the last 10 years I saw/used nothing else on a new install. I know stuff is different in especially the US, but well, US power system...I think we better stop here.
The big thing with fiber is not the cabling, but the termination. So if you can terminate yourself/get it extremely cheap, or use patch cables and coupler wall plates you could maybe get cheaper.
If you keep in mind that it’s only done with special certified subcontractors, then yes. I would never give that information directly to a company like X. And yes, also those special companies are more times shady than they should be, but still.