This app was mentioned in 6 comments, with an average of 1.33 upvotes
I know if two different apps for this.
1) https://play.google.com/store/apps/details?id=com.greenmile.highthere This one is called "High There" and is more specifically made for exactly what you were asking for. Now the big thing with this app is that it's newer and there aren't excessive amounts of people on it last I checked. Depending on where you live, you might find it hard to come across someone within a reasonable distance from you.
2) https://play.google.com/store/apps/details?id=com.massroots.android This one is called "MassRoots" and it's basically a social media for people that use medical cannabis. Now, as you can imagine, a lot of the people that use this to share pictures of weed, glass, concentrate, etc. definitely aren't actually medical patients. This one is a lot more populated than the last app because it's been around a lot longer. Also if you are a medical patient, a lot of dispensaries will advertise on this app. I've even been messaged by people trying to sell weed as well. I haven't responded to any of those because it sketches me out, but it's still that kind of app.
Hope these might help! I just moved to a new area which is a lot less populated than where I used to live and I've been looking for ways to find new people to smoke with and it's definitely not the easiest feat haha. Good luck to you with your quest :P
Det findes også allerede. Har før brugt det men det er mest udlændinge i Danmark der bruger det.
It has worked every time for me. It's full of people looking for a plug so you just need to search for people who sell. https://play.google.com/store/apps/details?id=com.greenmile.highthere