Disclosure: I built something similar called HODLings.
Fungible's architecture (local data, no vendor cloud) is the right answer for the crypto ecosystem too (arguably even more so).
Which is why I built HODLings: manual holdings entry (no exchange keys, no wallet-address pasting), live prices from CoinGecko, allocation and history charts, multi-fiat display. Same minimal- tracker shape Fungible has, but scoped to crypto.
Main failure mode is forgetting to export the backup before a browser wipe. Set a calendar reminder.
HODLings PWA is freely available at https://hodlings.app