For the 50 free spins bonus on registration? I dont think there is alternative since the 50 free spins bonus on registration seems to be specified for pragmatic only.
You can try to get in touch with the admin and ask them if they can offer you an alternative for it.
It is better if you are blocked to see pragmatic because you are from the blocked countries than you are able to see and play it and may lead you into a problem later.
Anyway, I heard that they are also offering other free spins bonus by email, have checked your inbox? Maybe it will work for you in case you get it.
Certain providers does really have that restricted countries and if you do see those slot games which are blacked out or cant really be able to access
then dont make yourself that trying to be pushy and accessing via VPN if you dont really like some potential problem or simply
its just a common reaction or approach which needs to be made.
In most cases, they are not blacked/greyed out but they are displaying normally and customers can often mistaken them as an available provider/game on their country but as soon as they click on it, there will be a noticed that will popped up or the loading screen will just hang. I can only experience it in Pragmatic Play provider but lately, I found some non-crypto casinos which Pragmatic Play games are playable.
I would be glad if a crypto casino can make a solution for it and I will play on them better because I think they are more trusted. For now, I can only use a VPN when I play the provider on a crypto casino and I'm lucky that I haven't experienced any problems with my account so far.