Dust under the main camera lens

Just found a grey sport on my iphone XS screen when trying to make a photo, it disapeared when I turned off the camera, so there is probably dust under the main camera lens. ( The outside lens is clean).

As my the warranty of my phone is expired in April 2020, I cannot turn to Apple dealer to switch the phone.

Is there a solution how to get rid of the dust?

So far I have googled the solutions:

• drop your phone with silicone case under 30 degrees to table/floor etc. to relocate the dust, hopefully it disappeares
• open the phone and take the camera out and clean between lenses with compressed air and lens cleaner.

Second one seemed to work on youtube but how about water resistance after that?

Or is it reasonable to open the phone anyways as I have nothing to lose.

It may not be water resistance after that, but I do not have to replace the phone immediately.

Any other solutions?