You can't find layer 1 blockchain tokens on DEX because L1 tokens usually list first there token on Centralized Exchange or build there own DEX in there blockchain however you can participate on IDO launchpad to make sure you can buy L1 tokens on early stage.
Yep, you're right, it's impossible to find coins in DEX (unless the wrapped version). Usually they will build their own DEX ecosystem later, for example like Oasis Network (ROSE) which is the first layer blockchain, at first they don't have DEX until finally they have Yuzuswap as their first and official DEX.