If you have an empty conduit, great, run fiber to each end. You have a switch on eack end with a SFP port on each end which is a 1Gb port. You add a LC module on each switch and connect up. With the switch in the garage, you now have a wired connection there. You can then add a Wifi Access Point, mounted on the ceiling. There are also AP's that will work outside in the weather. You can mount one of those on the outside of the garage and/or house. APs get power over PoE (Power over Ethernet) So you use an injector for each AP in the garage and outside the garage. Switch to Injector and injector PoE to AP So switch needs power and Injector(s) need power.
Get a Fiber cable from FS.com. Get one long enough to reach each end. You can coil it up at one end the extra length. You can of course go further if you want to have PoE cameras around your garage, inside and out? If so, then it makes more sense to get a PoE Switch with a SFP port. It's really easier than you think and not as expensive as you would think.