Can navsat_transform be used to transform a pose from latlong to odom?

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I'm using a gps to localize a mobile robot and ekf_localization_node together with a navsat_transform_node to transform the robot location into a local odom frame.

I would like to be able to send the robot gps-coordinates and use the functions from robot_localization to transform them into the odom frame. However, navsat_transform only publishes odom->utm and I don't think there are any latlong->utm conversion exposed to the user.

What I'm trying right now is to use the utm package in python to convert latlong coodrinates into utm and then using the utm->odom transform provided by navsat_transform_node to get the local coordinates:

utm_coords = utm.from_latlon(latlong[0], latlong[1])

# create PoseStamped message to set up for do_transform_pose 
utm_pose = PoseStamped()
utm_pose.header.frame_id = 'utm'
utm_pose.position.x = utm_coords[0]
utm_pose.position.y = utm_coords[1]

# get the utm->odom transform using tf2_ros
tfbuffer = tf2_ros.Buffer() 
tflistener = tf2_ros.TransformListener(tfbuffer)
T = tfbuffer.lookup_transform('odom', 'utm', rospy.Time())

# apply the transform
odom_pose = tf2_geometry_msgs.do_transform_pose(utm_pose, T)

It seems to work, but I would prefer to use the conversions implemented in robot_localization if possible, for consistency.