Hi Lisa, welcome to the forum,
It's not a market I have any personal experience in myself, however I doubt it would be a niche market. My instinct would be that it would be much more of a relatively mainstream market, than niche. That doesn't mean it would be a bad market to get into, but you would need to research it to really get a much clearer picture.
Well that's impossible to say without any data in front of me. Comes down to all of the basics, how many sellers are in the market, how many buyers are in the market, is the price you have competitive enough and so on. There is just so many factors that go into answering a question like that, that it's impossible to give an assured answer without haven't dome solid experience in that particular market unfortunately.
As for what other niche products might be good, well if I had the answer to that then I would be selling every single one of them myself lol. Developing a niche market usually comes down to lots of test marketing. This is where dropshipping really helps, because whiole it doesn't always provide you with the best possible price, it does give you the ability to do that test marketing without the expense of purchasing product upfront.
So certainly no harm at all in test marketing your products. The one bit of advice I would give here, is if you are going into baby monitors and breast pumps, then don't limit yourself to just those two products. See if you can incorporate other associated products in that genre to improve your chances of finding a market.