Suggest a business you can start with 100 USD or less in your country.

Maybe you can plant a smile on the face of a small child

Or you can help elderly

But I do not expect you CAN do your own job this amount in my

you can't have lunch .,dinner and a drink now days  for this much.

but if you give the $100  to charity to help someone learn something,you will open a future business that will last and pays you back later on.

$100 is enough to establish a small tuition or coaching center and home

One can open a Small tea stall in india but the fact is cost will go much higher as there is so much corruption

In some countries you can start toiletries (soap) manufacturing on a small scale for hotels under3 stars. Putting your humble brand name on a humble packaging. starting with100-200 units each and marketing it self. There must be a key differentiator as to why your product must sell as well, perhaps add some green stuff and go herbal etc.