Many brokers only show 1yr sharpe or perhaps 3yr sharpe (for example swedish nordnet has 1/3/5 year sharpe: https://www.nordnet.se/fonder/lista/jupiter-gold-silver-usd-... )... but very often stocks/funds go steadily upwards for several years in "good times" and then we have major drawdowns during turmoil like 2008 or 2020 etc. In these cases, a 1yr or 3yr sharpe can be very misleading.

Have you considered also plotting 3yr sharpe and 5yr sharpe over time? Perhaps the length of the sharpe ratio would be configurable in the calculator?

Are risk free rates matched to return dates? This makes it sound like the tool uses a single risk free rate for all excess return calculations.