A quick search on the word "Gramps" on Github shows the following other Gramps addons and other related programs not in addon-source etc..

Gramps2Gource - Combines Gource and Gramps to produce novel family history visualisations
Betty is a static site generator for Gramps XML files ancestry.bartfeenstra.com/
docker-gramps Create docker image of Gramps. Docker images are available at DockerHub.
Docker recipe to launch gramps and store my genealogical data
gramps-php-exporter - Export a Gramps database using python to a SQLite database and use PHP to display on the Web.
Gramps Web App: frontend This is a javascript frontend for the Gramps web app built on PWA Starter Kit.
- Genealogical progressive web app based on Gramps
WTFamily This is a slowly developed personal genealogical project. Genealogical research tool compatible with Gramps
GenealogyViewer - Web frontend for Gramps family tree
Web interface for Gramps Family Tree database
GeoFinder Read and verify place locations in GEDCOM and Gramps XML genealogy files
gramps-for-wp WP Plugin for Gramps , I wanted to show a Gramps Narrated Website within an iFrame initially but ran up against all sorts of issues when I tried to translate it into different languages.
Linux-Bash-GRAMPS-multi-report, Based on GRAMPS "Family Tree Manager" ( https://gramps-project.org ) this script will elaborate reports for all families iteratively

Trying out git versioning of gramps xml
GrampsCrossing This utility is intended to optimise the layout of a relationship graph produced with Gramps (genealogy software).
gramps-family-book Book generation script using Gramps database API. Produces a Latex document showing full information about the family.
Gramplet/Script to import into Gramps persons from Geneanet
gramps_powerpoint_family_tree_generator Generate a powerpoint slide with the family tree read from a GRAMPS exported CSV file ]
List of towns in Lithuania to import in to opensource Gramps family tree software.
A radial family tree using d3 force layout to interpret a Gramps xml file.

Addons

Unfinished

Poiggles - WIP plugin for GRAMPS-FamilySearch integration
My goal was similar to the hourglass view. Developing my visualization addon for gramps
Gramps Plugin - Noble Titles Report

GRAMPS example reports generated automatically - This project is a prototype for generating GRAMPS example reports automatically, and make them available online. belissent.github.io/gramps-example-reports/]

files2gramps Java lib for files to pack as a export into gramps database format.