We raised a support case to Nintex informing that opening a form from the mobile SharePoint application (official) and also from the mobile Teams application (official), it was not working from certain phones (IOS).
We got as an answer from the Nintex support that this was not supported and that they don't know whether this is going to be supported. (which a shame)
Hence I raise this user voice, to request the support of both Mobile apps, SharePoint and Teams, from any Phone OS. (Android, IOS, etc,..)