Alternatives to Google Messages

Works on MicroG?

Seems to work..

Open Source

AOSP/LineageOS Messaging

Simple and reliable. Already included in many custom roms

Pulse

Pulse is the ultimate text messenger. For Android, Web, Chrome, and many more.. Access messages everywhere. With Pulse, share what you want. Send pictures, videos, funny GIFs, audio, location, contacts, and more. Pulse is beautiful, and powerful.

QKSMS

QKSMS brings a refreshingly beautiful and responsive Material Design touch to the stale state of text messaging. Night Mode, customization, quick reply, group messaging, delayed messaging and much more.

Silence

Protect your communication in transit and on your phone. Silence (formerly SMSSecure) is a full replacement for the default text messaging application: all messages are encrypted locally and messages to other Silence users are encrypted over the air.

Closed Source

It would be better to avoid them