i believe the OP is asking from the perspective of having a renter or den / party room that in that space. providing that building with internet / streaming tv
after years of working residential internet service i’m going to tell you something no customer has ever liked hearing: switch to ethernet for as many devices as can possibly take it. wifi has an upper limit to its speed and that upper limit is divded between all devices. i am talking of course about your own house. not the rent sublet. move all your smart tvs to ethernet. tack long flat ethernet 5e to baseboards. cheap as heck on amazon etc. i converted my entire 2 br apartment to wired only in a single afternoon.
“but i have a gaming router with a million antennaes wifi is great” even if you have a fancy router or whatever, you’re still accumulating a ton of latency and lost packets. which then in turn, affects your renters apartment speed. technology still has an upper limit. pushing that much power through an atennae when a fraction of that power could be done over copper.
the apartment attachment, consider getting a ~500 foot ethernet cable. cat7 is, imho, rated for outdoor use it usually has kevlar reinforcement. you could easily run it through tubing or pvc and run a line between rooftops.
“but it looks ugly” the customers say. tough cookies. technology has its limitations, and if you’re serious about providing a solid internet connection to your tenant then you will want to go for function over form.
if you get a directional attenae for the garage space you would only solve a small part of the overall problem. to accomdoate an extra space, you’d need to improve the overall network health.