Android updates are only provided by the cell phone vendor and rarely are provided for more than 2 years from the time of release of the model. The Samsung Galaxy S8 was released in April of 2017, so I would not expect any updates of the basic Android operating system other than security updates and Google optional software after April of 2019, if that long.
I have a Samsung Galaxy A6 that I bought from T-Mobile earlier this year. I know the Android brand name was to disappear at end of 2019. I created a Samsung email account to use on the Samsung phone, but I couldn’t sign in with the Samsung email account to delete the Gmail account. Any updates for this? This phone has it’s own internet other than Google.