Your idea of how you could increase your assets while holding is quite a nice way but your absolutely not the first to think this way, well i wouldn't let my self to put in my money where I'm certainly not sure its save so prefer to hold my assets especially bitcoin because I don't have Ethereum, in a self custodian wallet which I'm rest assured it's safe to an extent even though it wouldn't be yielding profit as to when staked in any of the exchange.

Now from your research, Bitget Poolx has the highest ROI, one thing I can tell you is the lower the return you get in a year then safer your investment is but the Poolx for me is one of the highest kind of risk you would be taking as you're not sure what will be the next step of the poolx. Anyways everyone is entitled to his or her own risk if you can risk it then just do it.