Four years into OMS and now having almost no control over flatulence, I have given up somewhat and bought Shreddies anti-flatulence underwear (online from UK). Am about to see a dietitian regarding FODMAP, but got the underwear first.
Sorry to sound like an advert, but the underwear has been a godsend - I had got to the stage of not going out when it got too bad for one memorable, but short, period of time.
Shreddies uses a charcoal panel.
There is a Japanese product too, and they use some sort of ceramics in their fabric.As far as I know, they can only be bought online, and you have to get them sent to an intermediary Japanese online/purchase address (I don't exactly know what I'm talking about here - it all got too hard, which is why I opted for the UK product).
They're very expensive - say about $40 (Aust) a pair.