How do you mean merge?
It’s basically another messenger.
Signal is a great app to replace your messenger with. Keep in mind that it doesn’t save whatever media you post there in your gallery.
Matrix is another solution, but you’d have to self host that. I have no experience with it.
Threema is a swiss app which I think was pretty privacy respecting as well? It doesn’t use phone numbers either IIRC.
There is also this: https://github.com/alangrainger/immich-public-proxy
I think your immich gallery can even be private ( though the public proxy would need to be able access it ).
I have no experience with it though.
How do you enforce consistent backups of the database? Do you dump the data periodically? Copying the data on the docker volume won’t give you consistent ( and possibly corrupted ) backups IIRC if the database itself isn’t stopped.
Email notification and the like usually don’t work out of the box and require SMTP configuration. This is usually available in the app admin consoles or configurable through Environment variables in the console.
I’m not running it ( and I haven’t checked it for Monica HQ ), but those would be the first things I’d look for.
The .env.example file shows SMTP settings. The example file notifies to a logfile rather than an email.
https://github.com/monicahq/monica/blob/main/.env.example
# Mailing
# Set the MAIL_MAILER to 'smtp' if you want to send emails.
MAIL_MAILER=log
MAIL_HOST=smtp.mailtrap.io
MAIL_PORT=2525
MAIL_USERNAME=null
MAIL_PASSWORD=null
MAIL_ENCRYPTION=null
MAIL_FROM_ADDRESS=hello@example.com
MAIL_FROM_NAME="${APP_NAME}"
MAIL_REPLY_TO_ADDRESS=hello@example.com
MAIL_REPLY_TO_NAME="${APP_NAME}"
Signal used to do text messaging as well but they removed the feature. As they felt it was unclear when a message was fully encrypted ( signal message ) and when it wasnt ( text /RCS message ).
I don’t think there’s a privacy friendly chat app that also does RCS.