Pfsense is a FreeBSD distro, not some magic "hotspot enabler". The often mentioned OpenWRT distribution (Linux based) would be another option. Both of them already have basic captive portal software built in, still nobody bothered to create a proper Bitcoin plugin for them over the past few years.

The way how to do this is actually not very difficult or completely out of the box... it is just hard to monetize and unless you have a lot of people around that have BTC and would use them to pay for WLAN access, it would be very hard to profit from this at all (e.g. a hackerspace - but then again you'd likely offer free WLAN instead of charging money for something as basic as internet). This means you'd have to do this for the bounty here and personal interest. Apparently both are still not high enough to motivate people.