It will depend on how plausible his explanation is, but normally the anti-doping agencies are showing no mercy in those cases whatsoever and he can expect to be banned for years. But doesn't that mean he can still play for clubs in a different association like in Saudi Arabia? I guess it wouldn't hurt him that much if the consequence is that he is now forced to earn 30 million per year playing for a club in the Saudi Professional League. Unless I am missing something here and any ban imposed by the UEFA/FIFA? is valid globally or something, but I don't believe so.
After I read from several sources the news about how many years he will be banned from football some say only one year and some say several years but from my own assessment it looks like UEFA will ban him for several years because the use of doping is so deviant from football that it looks like it will be a very long time for him gets the ban and if he can still appear but in other leagues such as Saudi Arabia, the question is whether any club from Saudi Arabia wants to sign a player who has previously used doping or drugs?
I still imagine that because the majority of Saudi Arabia is Muslim and drugs are prohibited or haram and it seems that Saudi Arabia doesn't want to take this risk.
This is a very good question you brought up, but I think the Saudis also live by double standards all the time. Look when they signed Henderson from Liverpool, he is supporting the LBGTQ movement heavily and whenever he can he showed it with his sling and his shoelaces. Now they demand him to not do it anymore and he will indeed stop, which is a whole different topic and actually sad. But the same would probably go for Pobga. They say that it was an accident and that he now definitely does not take any drugs and then they would welcome him in Saudi Arabia, the country where the sheikhs don't celebrate parties without cocaine and girls on their yachts.