I hope I’m not sounding dismissive but I think most people using Monzo wouldn’t bother, or wouldn’t know/ care to look out for in detail. Many don’t even know DCC exists. Even with each country’s Wiki, unless I’m going to a really obscure place like- North Korea or something- I don’t check it, and I certainly wouldn’t scroll through a massive list of stores to find one I would possibly visit and find out about DCC (?) how would it be arranged? By location (?)
I think @Avishai’s guide is informative enough without needing to go into details about specific shops. I confess I go by the general rule of “always ask to pay in the local currency” instead of bothering about how it’s supposed to work 
Mostly just thinking it would be a lot of effort for something that could possibly differ, be difficult to organise, and run the risk of misleading people/ confusing them 
But you seem really enthusiastic about it, so maybe it could be something that exists elsewhere, not affiliated with Monzo so people don’t think it’s an official endorsement/ guarantee that you will be able to skip DCC.