In creating the DeFi platform, one of the main questions is to choose an optimal blockchain in terms of customer base, speed of transactions, fees, and competition. Another aspect of this question is what chains or protocols you need to support to enable traders to trade their coins/tokens on your DEX.
For example, layer 2 solutions like Polygon can be used – add-on chains that provide faster and cheaper transactions that integrate with the main chain, say Ethereum, and periodically register their dealings there.