Laser pointer in mobile

It's simple: I want a pointer, the “footprint” of which can be fixed (upd: for example, at a lecture or during an excursion).

Mathematically it is elementary. We attach to the usual mobile phone / smartphone with accelerometers / gyroscopes the usual laser pointer. We specify in the necessary point, we write down indications of sensors. Move the device slightly to the side so that the selected point remains the same. In this case, the sensor readings continue to be recorded. Everything, we have all the necessary information in order to determine the position of the indicated point relative to the mobile.

Possible hardware implementation is more complicated.
As a source of radiation, it makes sense to consider red LEDs, which are read a few fans . But you will need a movable collimator lens. You can make a movable ordinary lens by connecting it with a controlled three-step gyroscope. Well, of course, all this should be milded.