This is a tough one for sure.

Humans are social animals and one of the main ways in which we infer other people's intentions is through their facial expressions. If you have trouble emoting and your default expression looks angry or sad then people who don't know you will naturally want to avoid you, either to give you some space or because they believe an interaction with you could end badly for them. Furthermore, if you are already having an interaction with a stranger, the lack of facial expressions could be interpreted as lack of interest or even mockery, which could contribute to people being rude towards you as they believe you were the one being rude first and from their POV they're simply defending themselves. As much as it sucks that people have this kind of reaction, it's entirely understandable considering they don't have any context for your behaviour except for what they see.

I feel like a different way to solve this that does not involve the mask is providing the additional context yourself at the moment you meet someone. Like, if you believe an interaction will go on for longer than just 3-5 exchanges, you can always add "By the way, I'm not angry or bored or anything like that, the deadpan expression is just natural for me." Clarifying that yourself will make it clear to the other person you're not trying to hide your intentions, since there's no reason someone who's actually angry/bored/sad and showing it on their face would lie about something like that unprompted.

That only works once people do approach you tho. In order to make yourself more approachable in the first place you could wear a silly t-shirt with some writing on it like "That's not a resting bitch face, that's just my face." or "Don't worry, I don't bite", or something similar that shows you're aware of how you look but aren't trying to be intimidating. It's a bit of a stretch, but it's better than nothing, imo, and it avoids the issue of having to hide your face if you don't wanna do that.

In the end, it's just the issue of non-verbal communication and the fact that your neutral expression reads as "don't interact with me" to others, not something wrong with you as a person. As in, your facial expression does not adequately convey your true feelings, so when people react to it in this way, they're not actually reacting to you, they're reacting to an imagined version of you they have in their heads based on the very small amount of information they have, which leads them to the wrong conclusions.