ETFs made Bitcoin attractive to investors and it also made Bitcoin easier and safer to acquire for average people. I use a mobile bank and in my bank, I have an option to buy and hold ETFs. I can transfer my whole balance within seconds on my ETF account that's managed by my local bank and I can trade with ETFS instantly. After accepting Bitcoin ETFs, now I can do it in my bank. This way, I save lots of time, fees and most importantly I know that I'm secured because its managed by local and heavily regulated bank. I'm not afraid of hacks or anything similar because I'm protected. This is a huge benefit for the average person, it makes everything smooth and easy but it's only good for trading, I still prefer to hold my coins on my Bitcoin wallet.
I think that the biggest impact that ETFs have on Bitcoin is that it increased it's adoption, many people who were not comfortable with self custody embraced it. Also it helped build trust in Bitcoin, other people who were skeptical about Bitcoin became more trusting when institutional investors began to get in, they will reason that if this institutions have trust in Bitcoin they can too. Other than this assumptions Bitcoin was doing great before the ETFs were approved, it had already attained the reputation as a store of value. Overall I can say that ETFs made Bitcoin to be more attractive to both institutional and retail investors.