Im revisiting my own thread to share some experience using fiber extenders.
I've connected two locations with fiber trunks terminated with MPO. Thos go to fiber patch panels, converted to LC, and in general I now use various gefen extenders, I scored 2k60fps and even 4k60fps for ~100 bucks per set recently and been using them with great success. They are NOT ethernet, but it doesn't matter so long that I have enough available fibers. They usually are single strand OM3 devices, I buy LC-SC cable to connect both sides.
This results in at least 6 points of connection per link: Sender SC -> <- SC-LC cable -> <- LC-to-MPO cassete -> <- MPO fiber trunk MPO -> <- MPO-to-LC cassete -> <- LC-SC cable -> <- Receiver SC
There are actually more hops in my system. But it works mostly flawlessly for over a year now. Mostly: from time to time under some conditions I have some slight artifacts showing up. I believe this could be improved with better cabling but it doesn't bother me that much.
I've tried gefen, broadata. These are really good brands and can be had for very cheap for 1080p.
A similarly priced (but new) IP solutions (Ethernet) are generally slow and compression only makes them suitable for some emergency way of access or something. Idk but they're garbage. Some have USB 2.0 passthrough for keyboard and mouse.
I believe there are quite rare and expensive ethernet-based solutions out there but they don't pop up on ebay that much so I never had a chance to ttry those out.
When you have an option to pull custom cables and the distance is short enough you never need to bother with fiber, solutions that use CAT cables are super cheap and lag-free because they're also not ethernet-based and only use copper to carry their custom formatted signals.