In my experience with small ISP's they make 99% of their own headaches, the last 1% being provided by the small consultants who work with small ISP.

For fiber customer side issues are almost all wifi related, to the point that some operators will offer in home managed wireless options.

I used to provide support in an area where a provider had purchased a VDSL network in order to convert those customers to fiber. 20% of customers remained on VDSL for various reasons. 10% of customers had been moved to a dodgy hybrid fibre/last mile ethernet solution. and the remainder were all on fibre.

70% of support issues related to the VDSL customers. 20% the ethernet customers. and the remainder of issues were almost all wifi or power related.

They had a policy of charging customers 1000 bucks or so to convert them over to Fibre. Eventually they sold the business to a larger entity. 4 weeks of VDSL complaints, and the new owners gave everyone remaining on copper a free fibre upgrade.

Actually it was only technically VDSL. What they did was drop a fibre ntd into the old vdsl node, commission each port for a different customer, and then run a Ethernet / VDSL converter over the old lead in. The "upgrade" was just using the copper as a draw wire for the fibre cable. Nothing over 100 meters.