I am joining late but I also see your issue as being your son is the only one in his den. The den being Webelos 1.
I am quite sure the Cubmaster will try to convince you to become a leader. It’s how I became a leader 5 years ago and it was a fantastic opportunity to really help my son grow.
Now, I also lived the very small pack scenario and spent months with just my son or sometimes two kids at meetings. Personally, I didn’t join Scouts to be a Father-Son activity as I could do that on my own. So, we did move to a bigger pack and we went from 2 scouts to 12 now. Now he gets the interrelationships, teamwork, etc.
So, you can try the Cubmaster and expect you may need to lead your son until a new leader is found. Then get your son to draft a friend or friends so they can do fun stuff together. If that fails, your only other choice is another Pack.