The LGPL gives end users the right to replace the LGPLed part with a modified version, and users presumably cannot alter parts of a downloaded Unity app. So it does seem that software using an LGPL library cannot be distributed on Unity or most any modern app store and still be in compliance with the LGPL.
It's not viral, but it does give users rights that aren't natural under the app store distribution model.
It's not viral, but it does give users rights that aren't natural under the app store distribution model.