Speaking from over 10 years experience, there's no easy "conversion" from any Access form/report/export to GED format. As mentioned above, there appears to be no way to cleanly import a GED to wikitree that results in the proper generation of the biography section, though the GED categories for Name, Birth, Death, Burial, Residence, Marriage and Sources works pretty well, though FAMC and FAMS records get dumped into the wikitree Marriage subsection. You can see typical results (for my GED) here: https://www.wikitree.com/wiki/Veazie-497 [[Veazie-497| Henry Veazie]]
Off-topic (does not speak to "conversion" after use of a filter):
I have a routine to write to a spec 5.0 GED file from my database because I use it for reasons other than wikitree. E.g., Gedreporter imports it quite well. Note, however, the module is written entirely in Access Basic, if you want to go that route. Because of the FAMS and FAMC records in the GED, it's customized due to the way I maintain tables in my DB. It took weeks of coding and testing to get it to work well.
You might consider generating a report that arranges data in the order required for GED records. You will have to get very familiar with the GED field formats and record formats! If you generate such a text file, you can:
1) hand edit the file to add the GED tags to the data. However, that would require some fancy bookkeeping to keep track of the indiv and family records numbers.
2) if you're into programming, write some routines in Word Basic to generate the GED tags for the text file.