At only four weeks post-surgery, there is still significant swelling and scarring beneath the nasal tip skin and nostrils. Nevertheless, nostril asymmetry noted at this time may become less noticable but not completely resolve over time. This may be due to pre-existing asymmetry that is now more visible to you due to closer inspection of your nose or be a result of this remaining swelling.
An external split or gel application will not likely do anything to reduce or more rapidly resolve the problem. It will improve with time and not get worse.