Problem is FTS5 isn't included in the most default installation through package managers [I use Fedora]. And recompiling from source breaks a lot of things, as sqlite libraries are generally linked with all apps that use it.
I admit I only used sqlite through the go driver (https://github.com/mattn/go-sqlite3) where using fts5 amounts to one flag during the compile phase.
But SQLite's FTS5 has no support for the `offsets` function...