This isn’t “safe sleep” but I tucked a fleece blanket tightly around her crib mattress (as if it’s a sheet) it doesn’t move around and she’s too young to rip it out but the warm fuzzy sheet helps her sleep in her bed.
Maybe you can find a proper fuzzy fitted sheet
Halo sleep sacks solved this for me at 5 weeks - he only wakes up once during the night if he has his arms swaddled. He is 10 weeks old now
This isn’t “safe sleep” but I tucked a fleece blanket tightly around her crib mattress (as if it’s a sheet) it doesn’t move around and she’s too young to rip it out but the warm fuzzy sheet helps her sleep in her bed. Maybe you can find a proper fuzzy fitted sheet