Brother if your religion is Islam (assalamu alaikum) I can assure you that staking is NOT Riba (interest), it's different in the sense that it's more of a reward for securing the network rather than "money generating money" out of thin air like the ones who are in the banking industry, especially since there are no loans involved, and if there were no nodes securing a network then that network would fail to exist!
Please do not be confused from the websites and people who say these are "interest" payments, they're not the same as those that are forbidden for us as mentioned in the Holy Quran;
The Holy Quran, Chapter 2 Verse 275
"Those who consume interest cannot stand [on the Day of Resurrection] except as one stands who is being beaten by Satan into insanity. That is because they say, "Trade is [just] like interest." But Allah has permitted trade and has forbidden interest. So whoever has received an admonition from his Lord and desists may have what is past, and his affair rests with Allah . But whoever returns to [dealing in interest or usury] - those are the companions of the Fire; they will abide eternally therein."
I will give you another example, when miners on the Bitcoin network are "mining" for Bitcoin, they're using electricity and resources, this is similar to a trade.
They trade electricity, time, and resources for the chance of receiving a portion of a Bitcoin.
The same thing applies to the cryptocurrencies with a 'Proof of Stake' system, the ones who hold the coins have become the 'miners' and they are securing the network through holding their coins.
To summarise:
Bitcoin: They trade a large amount of electricity, resources and time for the chance to receive a portion of Bitcoin as a reward. = not RIBA.
Proof of Stake: They trade a small amount of electricity, resources and time for the chance to receive a portion of the POS currency as a reward. = not RIBA.
But to answer your initial question, yes you can hold your BLOCK without staking it. I believe to stake your BLOCK you must unlock your wallet and wait for a period of time before it will start to reward you.
It is generally a similar system, however the Proof of Stake system is more environmentally friendly which I see as much better.
And Allah knows best (Allahu A'alam).