I just tested this nice function. I installed that Gramplet, established an association of one person to another, and added the DNA data as a note to that association. The segment map is shown (Gramps 5.2.3 on Windows 11).
I have two problems:
when exporting GEDCOM the association is exported (ASSO and TYPE DNA), but the NOTE with the matching DNA data (csv) is not exported
mouse-over info is available on a matching chromosome part, but I cannot click on any element (documentation says: legend, y axis, …)
Just tested with Gramps 5.2.1 and DNA Segment Map [Gramplet] version: 2.0.6
Note that clicking on the Chromosome NUMBER or the NAME (in the legend on the default all 26 Chromosome layout) is what navigates the to the other representation (single chromosome layout) or person.
There was too much stuff going on in the bar in the y-axis (rollover "Tooltips) and it made using the bar too fussy. Likewise, the color swatch is not active because the various OSes rendered it with different vertical offsets. But the Name label was reliable enough to be a “hotspot”
As for the Note export to GEDCOM. Both the built-in GEDCOM export and the GEDCOM for Geneanet addon exporter created files containing the Association Notes. However, the GEDCOM Extension (GED2) addon exporter did not include those Notes.