Text messages sent from my MacBook Pro to non-Apple users (i.e. non i-messages) will no longer send. (They used to send just fine.) They hang and hang for awhile and then the "message send failure" pops up.
MacBook Pro 13″, macOS 13.4
iMessages sent to non-Apple devices sent through your Apple-ID account, then are LITERALLY sent over the cellular network using your physical iPhone, which must be powered up, and have cell service to forward the messages.
ku4hx has provided some good articles explains how just how all the setting must be set. In addition, sometimes a restart of your Mac or phone or both is required to get all the settings to "take".
Android may have made changes.
Web search finds: Set up iPhone to get SMS messages on Mac - Apple Support
Also https://www.airdroid.com/file-transfer/mac-imessage-not-sending-to-android/
messages won't send to android users on MacBook pro
