I wouldn't mess with the tire size. The tires are already stretched a decent amount on these wheels (the width of the wheel is 9.5, most 255 tires have a range of wheel widths they will fit but almost all of them that work for our car list their upper size as 9.5 wide... if you get a more narrow tire (the 255 part) there is a good chance they will have been designed to fit a wheel width LESS than 9.5 inch wide. While narrow tires work better in snow, I just wouldn't mess with it. It's less important than a good tire compound and the AWD of the Model Y.
The Hakka's are really hard to compare with more standard US stuff like Sottozero, xIce, or VikingContacts.
What I would suggest is this, plug in your car on TireRack and look at the winter tires they offer. The Sottozero are "performance winter" which means they're designed to run in temperatures below 45F and handle some snow but really do best on mainly clear roads. These will probably have better dry braking performance and maybe some better wet performance, but will do so by giving up some ultimate grip in deeper snow and ice. If you click the tire you can find a TireRack Tire Test that will give you a write up and some standardize tests they do. While it's not a perfect comparison since the tests were done in different years and maybe even different models of cars, usually you can compare pretty close between any TireRack test since they're always a BMW and the same test track. The VikingContacts would be the best for ultimate snow grip and perform REALLY well compared with Bridgestone (doesn't make a size for us) and even the older xIce 3 tire. Maybe the Hakka's are a little better, but if you're just worried about not getting stuck and having good control on ice and slush I would lump the VikingContact 7, Hakka's, and xIce all into the same group; they'll all be really close to each other and maybe only have different stopping distances of a couple feet for example.
It's unfortunate that Michelin won't have their xIce SNOW (the latest generation) in our size until ~Jan 1st. TireRack did a preview event of these (a test hosted by Michelin, so obviously the examples are picked to highlight the best results for Michelin) and was VERY impressed. It sounds like these will probably jump to the top of the list when comparing Bridgestone, Michelin, and Continental. If you're mainly working from home still maybe you can wait another two months for the xIce Snow (also have a 40k mile tread life warranty, the only winter tire that still offers a tread life warranty), otherwise I would get the VikingContacts if wanting ultimate "deep snow" (3+ inches) and ice grip, or the SottoZero 3 if you're just looking for a tire that stays soft and flexible in freezing temps and can handle some ice and mild snow (far better than all season, but not as good as a full winter like the Viking Contacts or xIce)
