As an NRI, can I buy Mutual Fund Units in the Portfolio Investment Schemes (PIS) account

No, you cannot purchase Mutual Fund units in the PIS account. You can only do so in the Non-PIS account.

As an NRI, can I buy Mutual Fund Units in the Portfolio Investment Schemes (PIS) account

No, you cannot purchase Mutual Fund units in the PIS account. You can only do so in the Non-PIS account.