Final Questions about Guest House/Yard coverage at cabin.

Hello

I've been researching some options for my parents to extend wifi to their cabin guest house and get the yard coverage decent. Wireless bridge is the only option to the guest house, so I think I've got that sorted with the nano loco station(https://store.ui.com/collections/operator-airmax-devices/products/nanolocom5).

I'd love for the access points in both the guest house and in the main house to be the same so that the wifi connection is seamless between the two. A few people have suggested UniFi access points(https://store.ui.com/products/unifi-ac-lite?_pos=1&_sid=9dc79d53a&_ss=r&variant=27263896769), but I'm wondering if that's gonna be beefy enough to reach the yard if it's located in the back of the house.

The house isn't too large and only two floors, so I'm not super worried about coverage in the house, but it would be nice if the yard got coverage decent enough to stream audio/video etc so my dad can watch a baseball game outside and such. I figure they could mount a second AP on the top floor in the side of the house facing the yard, but that might require more cabling than they'd like.

Would a mesh system in each of the locations be able to provide seamless wifi coverage and help reach the yard a bit better? I'm not quite privy beyond basic wifi setup. I also don't think they'd like to spend a ton of $$ (ideally under 400 or 500).

EDIT: forgot to post my janky measurement diagram here: https://imgur.com/IUK7uhP