I use Textfree. It’s a free app, you pick a phone number in any area code, I disable almost all permissions, banners, notifications, etc. you keep the same number as long as you use it once a month.
Location services, microphone, banners, ringer, use cellular data and about about everything else is disabled.
I have multiple apps in groups like “entertainment”, “finance”, “shopping”, etc and I hide the Textfree app on the second page of one of my groups. If I didn’t know where it is, I couldn’t find it.