Business model canvas is one of these things that make you think of stuff that you don't and can't know about.
A lot of the things on the business model canvas are not known at all. So at the best you can create hypotheses, but more often than not you never test them afterwards.
The number one thing you should do when starting out is talking to as many relevant people as you can.
- Your business idea is in a certain problem space -> talk to people who work in that field: engineers, managers, sales, marketing
- after talking to 15+ people you may have a rough idea what's generally seen as challenging -> narrow down what people need, how frequently the problem is encountered, ...
- create an MVP, test as soon as possible, find partners to work on the product
This is a very draining process and takes a lot of time and energy, depending on how easy you can acquire customer interviews.