You could be right about that because it will have same effect since they are both POS. I can't say ADA has more advantage than ETH but maybe because its cheaper than ETH and more people are able to buy this token than ETH.
Somehow there is no other else who filed ADA ETF besides Grayscale. It would be easier to see it approved if there are more institutions filing for it.
I think once the SEC is no longer an obstacle for Spot ETFs, everything hinges on traditional investors demand for ADA. If this demand is substantial, asset management funds will actively apply for ADA Spot ETFs, driven by the expected benefits from asset management fees. Currently, they haven't acted because they don't see a clear opportunity or are focusing on other more promising assets.
I hope Cardano will be adopted by the US government and many large companies, increasing the demand to own and trade ADA, thereby increasing the likelihood of an ADA Spot ETF being proposed and approved. Ultimately, I won't be able to invest in an ADA Spot ETF, I'll just wait for the opportunity to take profit on ADA in the market when the ADA price grows thanks to the success of the Spot ETF ^^