That’s not right. As long as they are excluded from DnD with their phone number, Android will let them through. It even says so in the settings (feddit.de still has image upload issues but the info states that “Even if messaging and calling apps can’t reach you, people that you choose here can still reach you through those apps”)
I’m running Stock Android 13 Fairphone 5. So if it’s not available for you it’s most likely taken away by your vendor. I remember my Sony XZ2 with Android 10 already having that feature 🤔