treenutz68 do you worry about keeping the number of your SIM card private and then utilize VOIP applications to make/receive legacy calls and sms?
This is actually the hardest part for me, I don't like the invasive practices of mobile carriers and the fact that the mobile network is inherently a tracking network (it has to be in order to locate and direct your calls). Security is out of the window as well on regular cell phone calls and SMS, plus the recent discoveries about all US carriers selling location data even when opted out of data collection just reinforce my aversion...
And yet, it's just way too practical to have internet access wherever I go. A lot of services I use (e.g. Signal) require a true cell number and working around that (secondary device, many cell numbers, opsec with airplane mode and where to carry which device) can be inconvenient and expensive.
My solution so far is to have 3 different cell phone numbers (business, private and for invasive apps like WhatsApp where I require them). The number for invasive services was bought via silent.link with XMR so it's not directly linked to my identity, the other numbers require KYC where I'm living which is unfortunate. I have a VOIP number as fallback solution, but it doesn't work reliably for me and won't help much if I show my real number anyway through some apps (Signal just recently introduced usernames to hide your real number, but it's not my only leak). I also use 2 devices and have all phone numbers registered on one device which makes use of different user profiles. I disable the eSIMs when I don't actively use them. The other device is WiFi only and used for my private conversations (Signal etc. is installed there, but not the eSIM I registered the account with). This is already too much effort, given that I can't control that most people in my network will just let Facebook, Google, Apple etc. read their phone book and profile me this way. But it's a good foundation in case I'm willing to take things to the next level, and it feels good to at least know my limits and circumstances.
But... I'm not glad with this solution, it's not fulfilling my threat model, I just have to pick my battles and compromise where it's not worth the time and effort to find better solutions. I also appreciate how privileged I am to even being able to afford such solutions that involves multiple devices and subscriptions, so I don't want to complain too much.
If you are less depending on true cellular numbers than me, a VOIP solution just as jmp.chat and compartmentalization over different social and professional circles might make a lot of sense. If I were you, it would be one of my later to-dos as I can be much more effective with less effort elsewhere. Using GOS will have the biggest impact, alongside password managers, mail aliases and simply getting rid of apps and services I don't need anymore. Then I'd get familiar with fine tuning my experience as described in my last post. Only after that is all cleared I'd dive into the world of mobile networks, anonymous/pseudonymous payment, proxy services (e.g. Matrix bridges for Discord/WhatsApp etc. if you couldn't get rid of these in Step 1) etc. Or in short: Make your life easy at first and incrementally step up your game in the more complex environments. That won't work on high threat models of course, in case the context changes...
Last but not least: Since you mentioned some sources for your education, I want to once again encourage you to use this forum. The mods and some users here have been amazing experts with very good intentions for me. Other than that I can in general recommend subscribing to The Hated One, Side of Burritos, the Closed Network Privacy Podcast and of course Michael Bazzels PDFs for easily understandable content. Mullvad, IVPN, privacyguides.org and Tuta have good blogs and articles. I don't trust Techlore or All Things Secured much as they make more mistakes and are often sponsored. From people like Rob Braxman and Tom Sparks I stay away as far as I can, because I just feel like I'm getting dumber and more misinformed by the second. Over time you'll find the right sources for you by cross checking everything. This is also true for this very post: Don't trust me! Verify and get a good feeling for who is out there to help and to misinform you. There are lots of snake oil salesmen in the privacy world...