What are the methods of usability testing of mobile applications in a situation of limited financial resources?

Question

Software testing

Greetings!
I will be brief. The application (native, Android and iOS) is already on sale, a fintech project (yes, comical).
There are still few clients (aka users), but the question is how it (the application) in its current form meets the needs of users.
Share testing methods that are as budget-friendly as possible. Need feedback.

Answer 1

1) 3F
2) distribution of nasharu

Answer 2

As an option, you can file the application prototype in Invision and let colleagues and friends use the prototype. The so-called corridor studies). In the original, you need to catch people in the corridors in the office).