Since you’ve already said you can’t run cable and you can’t get a line of sight to it the best option would be to see if you can get something like T-Mobile’s cellular internet for it or TP Link does sell outdoor mesh Network nodes but I don’t know if you could string enough of them together to reach. Plus it would be rather expensive buying the indoor nodes you need and then enough of the outdoor to reach all the way

https://www.tp-link.com/us/deco-mesh-wifi/product-family/deco-x50-outdoor/

Do you have any spare drives around that you don’t mind wiping the data from?

The way I would do it would be to get a new drive to be my new boot drive install Windows 11 fresh on it and then after installation and set up, reattach my old drives either internally or through USB adapter and try to transfer data off of them.

That would probably have the least risk of data loss and wouldn’t have the problems that setting up your Windows device in legacy BIOS mode would.

Sometimes yes sometimes no, really depends on the motherboard the type of RAM the BIOS you’re running.

Kind of a crap shoot too many factors to be able to predict if a certain configuration will work

The thing you’re trying to do? Save your cell data? The people who own those public Wi-Fi know you’re trying to do that and they put blocks and so people don’t use up all of their bandwidth trying to do that.