Look up computer generated holography! It is certainly possible to calculate a hologram of a letter which focuses at some different depth than the screen.
There are issues which arise from restricting the hologram to a real valued grid, like limited FoV and noise, but these are not impossible problems to solve and existing technology is already quite good in terms of image quality.
VividQ | FPGA Engineer, Holographic Optical Engineer, Senior Software Developer, Senior Systems Administrator | Cambridge, UK | Full-time, onsite
VividQ is a VC-backed, deep tech software company with world-leading expertise in 3D holography: the next generation display technology. Our expert engineers, mathematicians and computer scientists out of the Universities of Cambridge, Oxford and St Andrews have solved key technology barriers in the adoption of holographic display for mass commercial application. VividQ powers devices developed by OEMs across the US, China and Japan, establishing a new standard of display.
I have noticed that Google Shopping is blocking results for "N95 mask" in the UK, making it more difficult to find retailers which sell them. On the other hand there are thousands upon thousands of results on eBay/Amazon, most of which cannot be trusted.