Those are the products | services you would promote on your site vs a niche subject you would address to a qualified target audience (group of people)

Say Sci-Fi, what aspect would you discuss
https://blog.feedspot.com/science_fiction_blogs/

Possible programs
https://onemorecupof-coffee.com/best-science-affiliate-programs/

ONE niche, a website. Products and programs can be varied however all must be relevant to the niche.

In the first instance, I'd ask myself

Am I passionate and genuinely interested in my chosen niche, as I I'd be expected to write lots of content, it would motivate me to update blog with succinct original content worthy my visitors week in week out.

Would I be writing about it in a years time or two or more

Who would be my target audience, who would benefit most from what I have to offer. A Niche is A Group of People Looking for Stuff

A niche is not a product and needs to be focused on one topic (interest) so the niche website will help those with that interest.
A website with unrelated topics does not rank well.

When it comes to a niche you will be creating a website solely to help people with that niche. To do that you will be writing content providing information about it and how to solve its related problems; therefore it is important that you have passion for you niche and can identify the targeted audience that would utilize its related products and create your content for them.

Kyle always asks us to complete the following statement.
I want to help _____________ with _____________.

i would say you have three large niches there....
be careful you don't spread yourself too thin at the start or you will wait a long time before being able to get traffic without careful marketing...
good luck with what you pick
phil