[HELP] MAN Architecture

I've built fiber networks in the past for similar organizations covering an 80-100 sq mile area. So, plan has been a fiber network. Well, curveball thrown last minute was "why can't we just use 5G for connecting all our buildings? that's what we're doing at <X> where I work using Cisco 5G equipment."

I've beaten this issue to death. It simply doesn't make sense. We're trying to move away from a fixed wireless network that is expensive to maintain and provides poor performance and speeds to a redundant fiber ring to connect 40 or 50 facilities and a bunch of other "things" along the path geographically dispersed across what we'll call a Metropolitan Area Network (around 37 sq miles). One person in the executive approval chain has just enough IT experience to be dangerous and throw off months of planning and to disregard a collective 60+ years of operating this very type of network.

Of note, we're an all Cisco shop, mostly just 9300s with 9500s at our core. No frills. We don't currently employ any SDWAN technologies or anything of that nature. We run a traditional private MAN, all IPv4 private addressing with a few segments behind firewalls internally and our primary firewalls at the data center.

My current estimate for a full fiber build is around $5.5m with intent on pulling minimum of 96 strands in order to leverage dark fiber leasing to help cover any ongoing maintenance and even generate a revenue stream possibly.

I can't find anything on "site to site" connectivity using 5G, I mean, I'm sure it exists, but how real world is it, really? 5G isn't even a fully standardized technology yet. It's still considered a non-standard architecture. So why would I want to invest in that (when it's still going to need a fiber backbone) to provide connectivity for our facilities/users? I don't really know what it even looks like from a topology standpoint, my assumption is a whole other network overlayed on top of our existing.

Keep in mind, also, that I only have 2 network positions and myself. I feel like 5G is going to be a whole lotta extra to manage or we'd just have to lease from a carrier, but this person swears private 5G is where it's at. We are a very lean IT team and lean budgeted organization, this just all seems like a waste of cycles.

I may be completely wrong, I'm open to that. I've worked mostly within my bubble for years, so I know what works in traditional networking, just looking for some support and brainstorm items. Thanks in advance!