Is there a minimum amount of liquidity that is needed for a coin to trade properly on the dex?
As far as i know there is not
You can deposit any liquidity into the pool. But it must be on both sides, you cant only provide to one side.
There is no magic minimum for each trading pair to get the best 1:1 ratio when trading.
For example, my XYO the best ratio I found was trading 1,000 XYO since the liquidity pool is pretty low.
Just plug in a number, then raise the number or lower it to see how it affects the trade to find the best 1:1 ratio.
That’s what I do in my simplistic approach.