I've worked almost exclusively on https://info-beamer.com, a digital signage service for the Raspberry Pi. It all started as a for fun project while freelancing and turned into a profitable business. All while still being a lot of fun to work on. Unlike other Pi based solutions, info-beamer isn't using a sluggish browser but uses Lua/C at its core to use all the hardware acceleration features while still being pretty simple to program (see https://info-beamer.com/doc/info-beamer). The challenge is always to make all those feature easily available through a web interface. I'm currently improving that a lot by enabling users to create more complicated output without any programming knowledge. Getting to know Vue.js has helped a lot with that.