So we're just never gonna find out if he cures the red curse and saves his grandparents. W...

Sort of spoiler:
Before the epilogue when the main story ended it said he got famous because he created a potion that cured the red curse...it just doesn't show it lol so yes we can assume he save his grandparents but i do wish we got to see that

Thanks for reminding me of that part. I also really wanted to see their journey and him rescuing his grandparents.