what is the proposed collateral for validator node?

Hi tag390g

The minimum staking requirement is mentioned in the article, but just in case you missed it, here is what it said!

“Token staking

In the single-shard model, a validator must stake at least 0.2% of the total FTM supply (6,350,000 FTM) of their own tokens. This number, as well as many other network settings, will be subject to change via on-chain voting. They will also change when Sharding is introduced.”

Hope this answers your question!