I've been trying to work this out since the beginning of the year. This is anecdotally what I've done, what works and what doesn't.

Most of my solution comes from JMP.chat for my phone number along with the cheogram app for functionality.

Basically I got a number for friends and family. I got a second number to give to businesses that don't care about VoIP (my dentist etc). ($5 ea). Cons here are that SMS groups are limited to 10 recipients. This doesn't work for my large family chats (I can get them but can't respond). Another thing I dislike is since its XMPP based, all contacts are listed as their phone number if in a group, so it's hard to tell who's in it. (Solo texts show as names just fine). They have a premium tier that routes differently to allow more than 10 in a group text, but I've tried that twice now and the actual phone calling gets screwed up. So I'm still trying to get it all sorted out (and I'm not optimistic) It's also a service only in USA and CAN.

My original number that I've had for 20 years and all big tech have assigned to me, I ported to google voice ($20 fee)

Since my original phone number was a carrier number it is already assigned to all the stringent companies like banks. They continue to use it without knowing its now a VoIP number. I have all SMS messages forwarded to my email so I don't have to log into google ever. It works perfectly for 2FA. Shortcoming of this is that any group texts the email just says you got a group text, but a single source text the actual text is forwarded. I don't use it for groups so its not a problem but just mentioning it as a potential con. Then of course, its legacy so opening new accounts won't work the same way since its a VoIP number now.

I bought a hotspot from calyx. By far the most expensive part of my solution. But it gives me WiFi access without a standard carrier (it does use T-Mobile but calyx doesn't track you like they do). Check them out to see if it fits your threat model. It works out to about $50/mo but the biggest issue is that its an annual lump sum.

Another option I've been trying is 4freedommobile. They have decent plans and are focused on privacy. Everything runs through their app for encryption. But I've found the app lacking both in UI and functionality. You can't do group SMS (which is apparently coming very soon) but my biggest issue is they require google play services for notifications. They state they don't, but they do. Hands down it just doesn't work without it. So that's a deal killer for me.

Honorable mention is the premium service Elfani. I haven't used it but have considered it. Its very expensive at $99 a month but is secure. However I don't see much on privacy so I'm not sure how different they really end up being from their base AT&T provider.