Give user access to folder without changing ownership?

This is what access control lists are for.

setfacl -m 'u:programX:rwx' /etc/NetworkManager

The user account programX now has read, write, and traverse access to the directory, but does not have ownership access.

Bonus way of doing this on FreeBSD with its NFS ACLs:

setfacl -m 'u:programX:rwxD::allow' /etc/NetworkManager

Further reading

• Operation not supported with setfacl?

You can use ACLs for this, first of make sure that the acl package is installed.

After that you can run

setfacl -m u:programX:rw NetworkManager/