Tangentially related: I'd like to use litestream but my SQLite files are several gigabytes, is there a way to lazily download the db only once it's being accessed? (using something like userfaultfd maybe? just thinking out loud)
Verneuil (https://github.com/backtrace-labs/verneuil) offers that for read replicas, because backtrace as well has some multi-GB sqlite DBs. It's a VFS (loadable at runtime as a sqlite extension), instead of a filesystem.
I don't remember if that's in the docs; commit that adds the configuration field https://github.com/backtrace-labs/verneuil/commit/027318ba74... and commit for the enum https://github.com/backtrace-labs/verneuil/blob/e6697498f3ba...
(the actual implementation is nothing special https://github.com/backtrace-labs/verneuil/commit/b6bdfcf7bc...)
Issue for the feature: https://github.com/backtrace-labs/verneuil/issues/12