Hydranet is closed source to prevent thieves from copying code which took YEARS to build, makes perfect sense, besides their web-wallet/web-dex is browser based, similar to Metamask, so it's a completely plug'n play solution.
If it is closed source, it is necessarily centralized, and here you can compare it with BSC or any of the solutions in which the blockchain is managed from private nodes, which allows trading fees close to zero, but what is the benefit of it if everything is centralized and your funds can be frozen?
HDN is not a new token and L3 is not a hot topic so it will not attract enough attention.