Yes it's okay to allow your baby to sleep in your arms.
Babies love being held especially when they are under 1 year old and you can usually easily get the baby to fall asleep by rocking them in your arms.
I used to rock my babies in my recliner while holding them in my arms and they loved it and would easily fall asleep.
Just don't go to sleep yourself with the baby in your arms because you might accidentally lose grip of the baby or move about and harm the baby.
But as long as you're awake then it's okay to have the baby sleep in your arms.
Your baby might want to continue sleeping in your arms and lap well into kindergarten age but that is okay.