Coda has the most powerful tables I've seen of the Notion alternatives, and was a fair bit cheaper for my team since they don't charge per viewer or editor but per "creator". But unfortunately it's not open-source or local.

They have a pretty good [writeup](https://coda.io/blog/productivity/tables-not-spreadsheets) on why "spreadsheets" were avoided in favor of more traditional "tables" (a la RDBMS).