I think you could slightly improve the python installation steps by checking here :
You should probably not fork mautrix_whatsapp, just create a new repo and copy the files you need. You can push the files you modified directly here: YunoHost-Apps/mautrix_instagram_ynh · GitHub
If you plan to maintain the package you can ask to join the Yunohost-Apps organization, for instance in #freenode_#yunohost-apps:matrix.org. If not, then you can just open a pull request by first cloning YunoHost-Apps/mautrix_telegram_ynh · GitHub in a local folder, then copying your current project files in it, and then pushing.
currently the YunoHost packages are for synapse_ynh yes, but I think in theory it should work with dendrite too.
You can try to tweak the config file by changing the
homeserver:
# The address that this appservice can use to connect to the homeserver.
address: https://__DOMAIN__
# The domain of the homeserver (also known as server_name, used for MXIDs, etc).
domain: __SERVER_NAME__
I’m facing this exact issue too, regarding bridges for dendrite.
The bridge install fails so I cannot change the config file - or is it the idea to change that file beforehand and do a manual install somehow? Also, I’m not quite sure what needs to change on those “homeserver” lines as the code you mentioned is the same as what I find in the url you give up for the replacement code.