I haven't found a subreddit with dense source of data on Indian academia (career, education, research education questions) in reddit or in other sites. Sites related to academy (like https://academia.stackexchange.com/, i.e. this one) seem to be more general, and non-local. This new subreddit for indian academia, might allow having source for local data on the indian academy.
Here is the link to it: https://www.reddit.com/r/Indian_Academia/
You don't "announce" anything on the main board. Stack Exchange is explicitly a Q&A forum, so such links are considered to be spam, and are therefore always off-topic.
You may mention it in the chat room, but that's about it.
I consider it acceptable to make such announcements on Meta Academia or in chat, as they generally pertain to parts of this community. You can also try to get sufficient upvotes on a community promotion ad such that it is shown on the main site.
That being said, you are kind of announcing something that is likely viewed as a competing platform or community or a platform for questions that we do not allow for good reason. Either way, do not expect that such a proposal is met with much enthusiasm.
From a previous meta question here, it also appears that you could include a link to that in the "About Me" section of your profile. That is seen when someone mouses over your identification information, so if you answer questions about academia in India, people who find your answers useful will be more likely to see it.
This next part is perhaps more controversial, but if you encounter a question that is closed as off-topic here (such as polling questions or shopping questions or very situation-specific questions seeking advice) and you think that the subreddit might provide useful answers, you might comment with a suggestion to try that resource.
