You're P2P so you definitely want to do long-term, organic reach. Talk to small sellers. Look for people doing small time sells, like here on this forum's marketplace or even talk up those guys at Etsy.
It took guys like Bisq a really long time, but they recently (in September was it) had a big "promo day" just encouraging people and traders to get together for 1 day to open as many orders as possible. That's a pure crypto marketplace but the same can be done for your type.
BitcoinPRBuzz should be your first option. They look very professional, they also assign specifically one from their team to help you during the whole process who can also call you to know your needs etc.
You can also ask them, and they will send you some PDF documents about projects they wrote about in the past and the impact their press released gave (raised funds, traffic etc.)
I can vouch for these guys too. They're very good at press outreach and also have their own journalists that can really do a good job of talking to you and getting good ideas for stories - ideas you might not have seen yourself.
Just remember, exposure needs to be long term. I'd recommend a sustained campaign, rather than a sudden blitz.