Is it common with a toe implant to not be able to walk normally?

No. Typically if you had a toe implant, this should facilitate your walking to be better than before the surgery. Best advice is to talk to your surgeon to make sure the implant is in good position and working properly as you may also need some physical therapy to help.
No. The idead of an implant is to reduce pain and function and to allow normal walking. But it will take time post op to return to normal walking.