For folks who are actually going to go down this rabbit hole, yes the 3M 6800 series and the GVS respirators are great, and work with very similar cartridge-style filters. That said, a mask alone is not sufficient, and I really recommend you get a Tyvek bunny suit also to protect your skin against chemical exposure. Given the current weather, it's relatively easy to cover over the bunny suit with your outerwear like a hoodie so it's not even necessarily visibly super-obvious, and it will do a lot to help protect you. It's not just your eyes, nose, and mouth you want to protect but every area of your skin ideally.

Also tear-gas canisters are very hot when fired, because tear gas is produced and released via a pyrotechnic reaction inside the canister, basically burning a dry chemical to produce the gas. I recommend wearing a heavy (7mil or 9mil) nitrile glove with your bunny suit and over that wearing leather welding gloves or heat-rated mechanics gloves if you expect to encounter tear gas canisters so you can pick them up and throw them back.

Also, be aware that the filter canisters on most masks are only good for about 45 minutes to 2 hours (depending on exposure levels) when used in an environment where you are actively being exposed to the chemicals you want to filter. You need additional replacement filters that are /sealed/ in their packaging to swap out to in the field. Good luck out there.