Some sort of bond
Funding fibre to urban or rural areas is expensive, take up varies enormously and so telcos (OR etc) sensibly try to deliver where they get a return or subsidy.
There should be a system where you as a resident or business can provide that subsidy in return for share of the profits as more people take up the service.
We got FTTP to 50% our rural village after 6 years of working with Hampshire CC and OR. The other have 50% of the village had FTTC delivered as part of the Hants program. The FTTP 50% of the village has to raise a significant sum (£25k) to fund share the infrastructure. In the end Hants returned our money as the take up of Superfast was higher across Hants than expected and so OR gave them some money back.
Some sort of bond where local funding lowers risks for the telcos and provides a long term return for those who can / will provide the upfront funding would make sense and drive community engagement.