Unfortunately, I am not so optimistic. At least, certainly not in our lifetime when it comes to "millions".
My idea is simple: take the average liquidity circle that ~80% of people will need:
* goods: vegetables, meat, fruits, bread, milk, other farm products such as honey, jam, preserves, etc.
* services: cleaning, dry cleaning, electrician, plumber, home repairs, food delivery (from a private individual, where you can call the person and ask them to go to your favorite restaurant, buy you food, and you pay them in XMR)
... and start personally visiting small businesses, educating them about Monero, explaining how to use XMRbazaar, helping them set up an XMR wallet, etc.
A very important question that needs to be answered *correctly* is taxes. That is, if you openly tell merchants, "Don't pay taxes" they may get scared. In this case, the appropriate solution would be to explain that "if you want to pay taxes so badly, then, for example, if someone buys goods from you for 30 EUR, just take 30 EUR in cash out of your wallet and put it in the cash register".
You just never know when and how the state will send its dogs to tear you apart.
Also, I think such businesses need to start using Nostr. This way, they will:
1) get rid of the unnecessary noise of regular social networks
2) have a direct target audience ready to buy with crypto
