It is a bit of a fudge, but the process is there to be used.
Tripartite invitations give small countries that traditionally only send a small number of athletes an opportunity to include more participants, so Tonga qualifies on that count.
There are invitational places in 16 sports, which includes weightlifting (4 invitational places available for women).
The IOC reserves the right to accept late nominations (original closing date was in Jan 2019 but that was pre Covid).