GaN is newer technology and more expensive to manufacture. It can power laptops like anything else just in a much smaller package. I have a 65W GaN charger that charges my work laptop while on the go just as quickly as the official brick I leave in the office. You just need to pair it with a USB-PD rated cable that will handle the wattage your laptop requires. In my case, I ended up getting a 240W USB-C JSAUX cable. It’s stiff but does the job.