The only downside for metamask is add-on on Chrome and other browsers, no matter how careful you are you will make a mistake one day unless you don't use the PC to browse the internet, the more you have the metamask active and you are going from one website to another you are not safe, the mobile app is more safer
Wack, mobile app is even worse because any smartphone is the threat to your privacy. Mobile devices have motion sensors on board. Data from those sensors like gyroscopes and accelerometers are easily lifted to create the digital fingerprints of the walking manner relevant to owners of those mobiles. Various surveillance agencies practice to utilize those fingerprints to to identify any person of their interest.