There is that ABRA wallet looking to offer stock and ETF trading payable in btc.
but what ETF are you talking about specifically ? Bitcoin ETF ?
He mentioned he is not looking to buy Bitcoin ETF but he is looking to invest in ETF in general. So he is looking for a website where you can invest in ETF with bitcoin.
Then there is Abra but I no longer see their stock and ETF page on their website, this is a cached version