"I suspect it is easier / more cost effective to install something more advanced than an ONT"
"ONT" just means Optical Network Terminator and you'll still need one in a GPON network be it 1G, 10G or 25G (10G is being tested with the first customers here, while I see Switzerland IIRC someone is offering 25G already)
Being GPON connections already shared among many users, the ONTs are installed one per user - it won't be really effective to install one for more than one user. An ONT is quite cheap.
It's also usually easier to run a fibre cable in existing ducts (it can run with power cables as well without safety issues) than a Cat5e or Cat6.