Market Viability Research?

Does anyone have good resources for how-to evaluate micro-saas ideas?
As an example, let's say I am trying to create a podcast management system and want to see if there is any market for that in the space. I also want to evaluate features and see, if I create this, what is a viable MVP?
Do I just start cold-messaging people with podcasts and ask them their opinion?
Do I send them a survey?

Essentially, my question is what resources are there for evaluating an idea?
How do I determine my market's MVP (what features to include)?