Yeah, you can. I also do this because dm feature and other features of sololearn are not supported in my one device..😅
but in my both devices are phone, so I don't know about laptop.
But I think type of device doesn't matters.
Yes. You can do. Both the devices will be connected to the single account so if you learn from one device then the progress to the second device also. And if you will delete the progress in one device then the progress will also be deleted in second device
That totally depends upon the portal. What kind of portal it is. If it's a social media, shopping, blogs, or any general purpose. They usually allow multiple sessions.
Please don't confuse with Application and website. Your app is always logged in for you because that's made for ease of access.
codechef don't allow login at two devices. if you have already logged in and again trying to login at another session. It will simply ask you which session to continue.
Taking yet another example of banking. That's most sensitive, you can't log in two places at any moment.
So, it depends upon the provider.