Yes, the WKT plugin allows you to do that.
Just paste each geometry in a new line:
Which loads all 3 geometries as 3 layers:
If you paste geometries of the same type, they will be created in the same layer, unless you check "Create a new layer for every geometry."
GeoPackages are SQLite databases with a specific structure. You cannot just read geometries as "random" sequential bytes from a SQLite database, there might be fragmentation or similar.
If you want to do it low-level and without one of the fine libraries others suggested, the pure Python standard library way would be to use sqlite3 to open the file and then ...