Unless you're already an ophthalmologist (attending) in Sweden , ophtho is most likely out for you. Too competitive for IMGs.
See the NRMP data.
For GI, you'd have to go through IM. GI is the most competitive fellowship for IM. So at a minimum you'd have to (1) get into a solid IM program (which is tough as an IMG), (2) have a lot of relevant research for GI, and (3) the IM residency and GI fellowship programs would have to be willing to sponsor you for a visa. According to NRMP (2017), US grads had an 84.6% match rate into GI (319/377 US grads matched), while the total matched was 66.4% (493/742) which
includes US grads so presumably the match rate is a lot lower than 66.4% for IMGs. So it's potentially possible for you, but very difficult.
EM is difficult too. According to NRMP (2017), 78.2% of EM positions were filled by US grads. A lot of the rest are by US-IMGs who don't need a visa. But like GI it's potentially possible for you, just very difficult. You definitely need to do a couple of rotations in the US at some point and get good SLOEs because SLOEs matter a lot in EM. By the way, you can work 40-50 hours in EM, but it's not easy work (e.g., mutlitasking, pace can be intense)! And a majority of your career will be nights, weekends, and holidays. So it's limited hours, but certainly not regular hours.