The basic principle for sharing research data is that data should be as open as possible and as closed as necessary.
More informations:
Open access – activities of researchers and doctoral students
NCN open access policy requirements
Addresses of free repositories
Legal basis: Ustawa z dnia 11 sierpnia 2021 r. o otwartych danych i ponownym wykorzystywaniu informacji sektora publicznego (Dz. U. z 2021 r. poz.1641)
https://isap.sejm.gov.pl/isap.nsf/download.xsp/WDU20210001641/U/D20211641Lj.pdf