There is decentralised finance (defi). One example of application is lending your money (in stablecoin or token format) in a lending protocol of your choice. You can expect a very good yield compared to traditional finance. Aave and Compound are the most famous. This is one type of the many financial applications developed on Ethereum's smart contracts.
Indeed I think they don't ship the whole browser package.
What they might actually do is to locally launch a HTTP server which renders the app if you call it on any browser (localhost:8080 in the examples). The chrome of the app is actually a thin layer that use the default OS web browser. That is why the memory footprint is much less higher that alternatives like electron.