It's pretty simple to upgrade a laptop running windows to a new AC-level wifi modem. The modems are standard and usually accessible on the back behind the service cover. I just did so on my laptop and it only cost me $ 35 for a new modem chip. Most laptops are using 2x2 antennas so you have to stick to those vs the 3x3 models. I chose the Intel 7260AC chip which supports AC1200 and it seems to work quite well. Need to install latest associated driver with it and don't use the default windows installation for it to work best.
Dell is a good platform to do this on as they don't typically have white lists in the bios. HP and Lenovo can be a problem however as they do use white lists which only allow part numbers from their own inventories. I didn't know this when I purchased my HP laptop a few years ago and had to install a hacked BIOS for me to be able to do this but it now works very well.