Yes, there's an option in the hamburger menu to edit queries manually, and that will allow you to type in (or paste in) the query by hand.

Re. the saved query restriction - I am planning to work on this app in the long term, which unfortunately means I have to monetise the app in order to sustain development work.

I believe restricting saved queries and saved connections is a good compromise to allow casual users to try out all the features the app has to offer, without imposing a time limit.