Keywords OR Communities when it comes to Reddit ads with a small market and a high-pre-existing intent?

Hello!

TL;DR further below, full story here

I'm about launch a product for a small language of Europe. This is not a language people would learn for cultural or touristy purposes like people would for Italian, French or maybe Japanese.

The product would make more sense for people that have decided to move there for work or as a life decision, or planning to do so.

So it's fair to say that my potential customers are few, but would have a fairly high pre-existing intent. I'm not selling a new phone, HDTV, brand of coffee or of sneakers... products that anyone could be tempted by. I'm likely totally irrelevant to 99% of people.

BUT I do like the idea that Reddit allows to target specific communities. And the language of my product has its subreddit, and there is one for people planning to move there, and for the country, and for a couple of famous things the country is good at. And major cities. This seems so much better than what Meta doesn't allow you to do.

TL;DR HERE:

But I've read a bit about using keywords vs using communities and I'm not sure. So my questions are:

1. What are the pros and cons of keywords vs communities for a product like mine?

2. I'm tempted to implement a Reddit Pixel, but I fear my numbers will be so small (I know they will) that it could backfire and that little data might lead the targeting astray

3. Are there any guidelines for the number of impressions you should budget for and the size of your target communities? A friend of mine is doing something similar and he's certain he's overbuying impressions, which he think could backfire in many ways...

Thanks!