I have something similar that was discussed here few months back, the whole thing is in a org file, i can add summaries etc and each becomes a hugo blogpost, it's not as interactive as OPs submission but works ok i guess.
Feel free to fork the repo and run locally! https://github.com/pmillspaugh/weeksofyourlife
Maybe I could add an export feature that downloads the data in a .csv or something. The URL storage is definitely a bit wonky, but more robust persistence felt like overkill (maybe I'm wrong about that, though!).
Only reason for asking it is that I was thinking of something similar and started keeping a daily diary in text files.
Can add summary of sorts for weekly thing.
But if someone is like me and has years worth of data, they'd want to be sure that data is going to be there in future as well.