Looking for Advice - New fiber terminated to demarcation point, >300ft to business suite..

I am more of a systems guy, in charge of a satellite office turn up. We have fiber being provided, pulled to the office space, terminated at the buildings demarcation area. The distance required to pull service into the suite is right around that 325ft max for Cat 6 copper.

I have very little fiber experience in this scenario. I am being told by the low voltage contractor who is handling the demarc to suite run, that we should look at media converters and fiber to the final service destination.

This is the ONT we are expecting, a Calix 762. https://i.imgur.com/N65FS1x.png

Seems a bit crazy to go fiber->copper->fiber->copper as Ethernet is required for our router, but that could be my lack of experience.

Just looking for some ideas of how you pros would approach this, any good media converters you would recommend on a budget, what type of fiber, any other suggestions on proceeding in general?

Thanks,

Mike