In-house fiber network

Not sure if I should post this here or over in Technology, but here goes.

So I need to run two Gigabit (or better) network cables from the main switch in the garage into another room.

The problem is that that room is a shelter (small bunker), which according to Swiss regulations means no holes in the walls, and the 'door' is an airtight 35cm thick slab of reinforced concrete and steel. So the only way into that room is a small conduit for electricity. There's no way two Cat7 cables fit into that conduit, and power and data cables are not allowed to share the same space anyway. That means the only viable option is fiber - and, considering the conduit's dimensions, only fiber without a connector will go through.

There are copper/POF adapters readily available (such as this one), and they would probably do the job. However, POF is effectively limited to ~1Gbit half-duplex. If I go through all the trouble of installing fiber, I don't want it to be inferior to the existing Cat7 copper cabling. If there's a multimode solution that doesn't require me to buy two four-figure Cisco switches and five-figure tools, I'd much prefer that. Has anyone here heard of such a thing?