Shared internet access for multi-family housing complex

(Mods, please remove if not appropriate for this sub)

Hi all! My dad is building a 16-unit apartment complex in an area that has gigabit residential fiber, so I floated the idea of offering free wired internet as a tenant benefit. My hope is that tenants can plug their router's WAN port into a provided cable drop in the closet, tweak some settings, then bam, free 60Mbps up/down. I myself have an electrical engineering background but I'm not a networking expert by any means, so I have a few questions for folks here.

1) Will this setup be kosher from the ISP side? If they end up insisting on us getting a business 1Gbps connection, it might not be worth the monthly cost. Or, what are the odds they'll just insist on installing an individual ONT for each unit?

2) How difficult will this be to setup and manager? I assume I will need an enterprise-grade router to enforce strict QoS. Each tenant router will have to change their WAN settings to specify their own IP address and use the building router as a gateway. How can I guarantee a tenant in Unit 3 cannot access file shares on Unit 12's LAN?

Thanks!