In mobile and desktop use i want to use Search bar not a Search icon. It would be great the search bar to be open all the time. It’s more user friendly when using a bar instead of icon.
If there is some design solutions to that I would be thankfull,
If you want it to be open at all times then the best solution for mobile is to append the search bar at the end of the header, or move it to the footer just for mobile and have it opened at all times.
Besides that, you can’t do much without the icon on mobile. That’s what I have seen in the stores for 7 years now.
Note: Just follow what Ujjaval suggested for desktop but I wouldn’t suggest that solution for mobile, I don’t think that’s user-friendly because the size of the screen is too small.