It appears neither PSC or PPSN is required according to info on MRCI site as below.
''..The Irish Government has confirmed to MRCI that all people – documented or undocumented – can apply for hardship payments and access information from social welfare services free from fear during COVID19. You will need to give the Department of Employment Affairs and Social Protection (DEASP) personal information to apply for hardship payments. These services will not share your information with the Department of Justice and Equality during COVID19. It is safe to apply. ''