2fa is a must-use security measure for those who gamble online, but I've read that 2fa authentication can be bypassed by hackers. I believe this is related to losing your mail account to hackers. Google 2FA authentication just got an upgrade today and now you can backup all your 2FA code with your Gmail account, way better than before but losing your Gmail account will put you in a big trouble.
The reason why casinos don't go for developing mobile applications is that players don't demand for it much and as said, there can also be security threats since an application can be more vulnerable to exploits than a website.
I think the same, I prefer to play in a casino with a big screen where I have a lot to do, a lot to observe and I have options to react or use game tools that are sometimes much more visible on large screens on PC than on one of a phone, and even though there are phones that are quite large and with spectacular screens, I think that the Android versions change the game environment, and that is something that at least I don't like, aside from the fact that I don't have much skill using lso phones and less in games.