The description for sqlite3_deserialize sounds like it meets your use case. I don't see Pascal FFI definition for sqlite3_deserialize() in current FPC SQLite3 bindings, so you'll have to add it in your own code.
Probably has to do with, that the Header-Definitions for SQLite are Version 3.14
and with SQLite 3.36 they changed the compile-option from opt-in to opt-out
Meaning: Before 3.36 you had to include explicitely -DSQLITE_ENABLE_DESERIALIZE when compiling SQLite, so probably 99% of the users didn't have the interface in their library ("of-the-shelf library")
With 3.36 and later, deserialize is compiled in per default
I've already asked a few times, if there will be an update to the SQLite-Bindings