For small businesses, a president taking power can immediately affect business. Small business owners make decisions based on their expectations of future, colored by their emotional state, so if they believe that a Republican President will be good for business, then they’re more likely to order new machinery, hire an extra person, etc. In an ecosystem of small businesses, that optimism feeds on itself.
Happens in big business, too. S&P500 gained 3+% the day after election, which (if you don’t believe the daily stock market is just gambling) presumably means that ‘the market’ expects 3% more growth out of all those companies, just by Trump’s win being formalized. Stock price up makes it easier for companies to raise capital to expand, buy out competitors, etc
Neither of those things is “the economy,” but they can feel like it, if you’re close enough.
Sensors. Especially sensors in your living space where fans or other noise from the proper server would be distracting, or in a tight space - inside your HVAC, for example - where a proper server wouldn’t fit.
Media front-end. Most of those SBCs are more than enough to run a kodi or jellyfin frontend, fanless for minimum distraction.
Robot. Low power requirement so it could be mobile; but there are lots of stationary possibilities. GPIO libraries are great for running servos and there’s tons of libraries to facilitate.