Yes, but on certain conditions. The best scenario is to test one niche at a time if you're starting out. This will help you determine which target market clicks with your digital marketing strategy. Remember that tending to one niche involves setting up your platform, creating content, getting feedback, engaging and growing your community, sending emails, and running events. So you'll have to replicate all these efforts if you decide to cover two or three niches.
When testing one or three niches, you should give them your commitment, including monitoring your analytics, for six months to a year. Spending just one to two months testing a niche won't help you find out which of your efforts are delivering results.
Another possibility is to find two related sub or micro-niches belonging to the same broad niche. For instance, you can combine budget tracking with financial education. Or you may create content related to hotel accommodations and nearby restaurants.
When it comes to featuring different but related affiliate marketing products, you can distribute them across your various channels or through different campaigns. Choose which items to promote via social media, YouTube, blog, or e-book.