I personally recommend scarfs or bandanas. Or better yet, if you don't have to worry about job loss, and wish to truly express your freedom, nothing at all. It's normal for people who are actually quarantined for being confirmed to have an illness to wear a mask if you need to go out for necessity. It is not normal for the average person to do so.

If you are protesting something, it is not normal for corporations to tell you what you can protest against. The fact that we are being told what and how we can protest should concern you, it should concern everyone.