This is essentially a low cost PoE powered switch with two ports that will be inline somewhere along your outdoor ethernet run. One of these will allow you to reach your destination and yes it will work. A much better question would be - should you replace a working gigabeam run with this?

As a general guideline - long distance ethernet outdoor runs (with/without repeaters) are not optimal from a network protection point of view. This long outside/underground run is an entry point for EMI and differential grounds issues. You will need larger cable to avoid PoE issues (think 23AWG), shielded, and correct jacket for its environment. Ideally isolated surge protectors on each end and supports PoE. You can direct bury the cable as long as the jacket supports it but it is always a much better idea to put it in some conduit to protect it. Somewhere mid point you will need to install the PoE switch(repeater) in a proper box for the environment you are in.

Instead, a fiber run with a couple of transducers at each end would be optimal and have no risk of EMI introduction and overall will be about the same cost. No need for a midpoint box (unless you need a pull box). Since your going 450', just pick up a 500' premade fiber cable, a couple of ethernet transducers, and install it in some conduit to protect it just like you would have for ethernet.

If you really have a need to replace the GigaBeams, something like these products would help you. Or any other similar items - you are looking for OM3 cable with LC connectors, and LC to ethernet converters. Naturally converters come in various price points depending on company, quality and speed.

https://www.amazon.com/gp/product/B07YWJV5W6 (150M long outoodr OM3 LC-LC connectors)

https://www.amazon.com/gp/product/B09P4ZS4QN (LC -> SFP -> gig ethernet) pair.

Again ask why you really want/need to replace the working GigaBeams. If so - go fiber - don't go ethernet.