There's one layer of swiss cheese that I would never omit:
Respirators.
This is the only layer that can prevent close-proximity transmission.
As long as you're wearing one that you know seals to your face and isn't soaked or super old, it's going to protect you from all the invisible ways #TrojanAir can get into your nose and mouth.
And even if you haven't proven that it seals, it's damp, or you've worn it a bunch of times before, it's still going to provide more protection than any other layer(s).
Please, please don't think you can compensate for being unmasked by utilizing combinations of other layers.
All the other layers are designed to make a respirator more effective or provide backup in the event a respirator lets a bit of something through. Even vaccines were trialled in the context of universal masking; their original efficacy numbers are a product of that environment.
If you can't get your hands on any respirators, reach out and I'll connect you to someone in your region who can help. If I have to ship you some myself, I will.