Can NRO account be linked to demat?

Yes, an NRO account can be linked to the demat account.

If an NRI intends to invest on non-repatriation basis, NRI can link their NRO bank account to demat account to invest in stock markets, mutual funds, IPO, rights issue, F&O etc.

The demat account linked with NRO account becomes NRI Non-Repatriable Demat account. The sell proceeds of stocks from the linked demat account or any corporate action benefits like dividend due on the shares held in such demat accounts get credited to the linked NRO bank account.