How to rank a one page web application?

I am planning to create multiple websites using custom coding (PHP) which will do some job. For example a loan calculator or anything which will do some calculation. But it’s going to be a one-page application. So how can I get traffic to these websites?

Note: This is just an idea that came into my mind, the actual idea has very low competition.

Make a blog alongside to send traffic to the tool. It depends whether you want to make money with tool or use tool to attract traffic.

If the tool is a good one, you will attract visitors like Uber suggest does for neil patel blog.

However if tools is for monetization and you want to generate traffic then drive traffic via blog and sale the tool as a solution to a problem.