Institutional investors don't waste their time on penny stocks, so none available there.
Retail investors must hold most stocks in a cash account (rather than margin) if the price is below $5, so again no availability.
Be careful if an offshore broker claims to make this possible. If the broker is not located in the US, you have no legal protections. Very easy to get scammed.
NO you can not legally short a penny stock - no reputable broker would permit such an order
The broker can not borrow the stock to make delivery since such stocks can not be used for lending
Penny stocks can not be used for margin, therefore the requirement for shorting would be that the short seller would have to carry 100% of equity in their account in order to sell short.
Short sell makes you a more diverse and flexible trader because you can buy breakouts and short sell when the price drops. So this gives you the unique ability to make profits on the way up and on the way down.
It will cost you more to short a penny stock
Best of luck
If you have to ask, probably not, sorry I don't mean that to be insulting.
It's just not likely available for you. You can borrow and sell the shares, but this is still a literal otc, phone in hand, trade, like the old days.