Estimate demand (e.g., through search engine keyword volume), estimate monetization (e.g., by working out how much you can charge in your niche) and then decide whether it is sane for more than one provider to exist in that specific niche.

If you decide to compete, realize that better execution followed by better SEO/marketing will always prevail over any head-start a competitor has. (SEO positioning takes quite a long time, so make up an excellent website and start SEO/content-marketing even before you have a product ready.)

Also, being the very first in an uncharted niche might be a disadvantage as opposed to an advantage. If you manage to learn about your competitor's mistakes (e.g., analyze on-site or app store feedback, etc.) and prevent those mistakes in your own product, you will not be wasting considerable development time/resources as your competitor did.