If a site such as a crypto exchange says "Scan this code with your Google Authenticator App", then you should be able to use any 2FA app. I have certainly done this in the past and it works fine.
I understand now, the point is we can scan Google 2FA barcodes with other applications running 2FA. So far, I thought that if the choice of service was only Google 2FA, then we could only use Google 2FA. From your explanation, I tried to scan the 2FA key
(on the service mentioned Google 2FA) using aegis on my phone and it worked. I just understood this today, and I was wrong all this time thinking that Google's 2FA can only use Google. Thank you very much for this knowledge