Hubby and I have been increasingly using our Up accounts. Up is a subsidiary of Bendigo Bank, and the app is the only way to do things.
Their setup is: Each of us was given our own account when we signed up. We've got physical debit cards for these accounts. You have the option to create a joint account with another user. By default this account only has a digital "debit card" but I think there's an option to request a physical card. From your two accounts (solo and joint), you can subdivide into "savers" which look and feel like separate savings accounts but on your statement they're rolled into the main account. You can have lots of savers if you want to. These can't have cards attached but earn interest. We use them to hold money for different purposes. I've never tried closing a saver so I don't know how that goes. I'm honestly not sure what the use would be in regularly opening and closing them. Just change the labels as you need to. Leave one empty while it's not needed; repurpose it next time you need a new one.
Everything is done through the app, and everything I've needed to do has been straightforward.
Tbh, it doesn't cost anything to open a bank account. If a bank you're considering doesn't have any monthly fees (Up doesn't, UBank didn't when I tried them a few years ago; maybe your other options don't either) then you can just make an account and try them out. A bank that is online like you want will let you sign up online. See if you can do the things you need to do online/in the app. If yes, you have a winner. If no, keep looking.