You might be interested to learn some history of societies without state-issued currency. The book “Debt: The First 5000 years” by David Graeber has lots to say about pre-modern systems of account. I’m aware there are some criticisms of the book so I don’t want present it as absolute truth - but it is an interesting on read, and it cites lots of anthropological studies.

One of the points of the book - and I see there are also other anthropologists who take this view - is there is no evidence that there has ever been a barter economy. Economics curriculum typically talks about prehistoric barter as an introduction; but it looks like the barter story may have been made up by Adam Smith. Smith’s “Wealth of Nations” is highly insightful, and even predicts problems with capitalism that we currently face. But he probably didn’t have the anthropological background to write authoritatively about economies of prehistoric societies.

Graeber does claim that there have been times when barter has been a stop-gap when there is a problem with money supply. So that’s a case where something like your app might come in,

When barter has appeared, it wasn’t as part of a purely barter economy, and money didn’t emerge from it—rather, it emerged from money. After Rome fell, for instance, Europeans used barter as a substitute for the Roman currency people had gotten used to. “In most of the cases we know about, [barter] takes place between people who are familiar with the use of money, but for one reason or another, don’t have a lot of it around.

These were temporary situations. The fall of Rome probably seemed like the end of the world to some people at the time. But new societal structures and currencies filled the gaps.