Guitar Pro still supports also tablature export in ASCII format, so it should be quite possible to create a fully working tablatures from .gp5 files. We do not know about any other program that could produce ASCII tablatures from GP5 projects.
Convert Guitar Pro 5 project to ASCII text characters file.
We found 2 software records in the database related to .gp5 to .ascii file format conversion.
Microsoft Windows software - convert gp5 to ascii on Windows
Multi-track editor and music composer for guitars
Convert from gp5 file format
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned gp5 to ascii. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
Apple macOS / Mac OS X software - convert gp5 to ascii on OS X
Mac version of the popular tablature editor