In Canada they have to let you do at least some minimal solo flying, as it is legally required:
421.38(1) Seaplane Rating - Requirements
(a) Experience
(i) An applicant for a seaplane rating shall complete a total of 7 hours of seaplane training, including:
(A) a minimum of 5 hours dual instruction, and
(B)
a minimum of 5 takeoffs and landings as sole occupant of the aeroplane, except for two crew aircraft, in which case the takeoffs and landings shall be done as pilot-in-command.
(ii) The following exercises shall be included in the seaplane training:
(A) taxiing,
(B) sailing,
(C) docking,
(D) takeoffs,
(E) landings, and
(F) as conditions exist, operations on glassy water, rough water and in crosswind conditions.
(b) Skill
Within the 12 months preceding the date of application for a seaplane rating, an applicant shall have successfully completed a qualifying flight under the supervision of a Transport Canada Inspector or a person qualified in accordance with CAR 425.21(6) by demonstrating the level of skill specified in the
Instructor Guide - Seaplane Rating (TP12668).
I did 1.2 hours solo, giving me 10 full-stop circuits. Not much, but better than nothing.