"* obviously from the safety of a disposable, unregistered cell phone purchased with cash."
I don't know how it works where you're from, but buying burners has several barriers here:
1) Most shops won't sell a burner without a credit card. Cops don't like it unless they can trace who bought the burner.
2) Most places that sell disposable credit cards require a debit or credit card transaction for the same reasons.
3) Virtually every place that sells either burner cell phones or disposable credit cards has video - and often audio - surveillance.
In order to completely "wash" all traces of the purchase you should go through a few steps:
1) Buy everything in disposable credit cards.
2) Case joints that sell disposable credit cards so that you can ensure they won't be able to track you.
3) Use a mule, but never the same mule twice. (Always incorporate a backup plan!)
4) Consider buying a handful of "high value" disposable cards then using them to buy multiple low value ones at different locations. Additional buffer helps.
5) Do not invest any of your now anonymous ephemeral money into a burner with contactless payment options. You do not want any correlation of your purchases with the phone number, because if they can put your purchases and your number in the same place at the same time, they will pull your image from a camera. Tower triangulation is not accurate enough for this. Keep the phone simple. Basic voice and data. No GPS.
6) Don't use bitcoin; it's trackable. Some altcoins aren't. Do your reserach.
7) Use anonymouse credit cards to purchase hosted/colocated server space in foreign countries in order to do your online shopping/hacking/talking to journalistic sources/posting dissenting views against your government/etc.
8) There are a number of shipping forwarding companies if you want to buy things online. With a little bit of work you can even find storage facilities or virtual office providers that will accept deliveries on your behalf. Better if they are located in a neighboring town, and if you get at them using some transportation method (taxi/lyft/etc) that doesn't take your picture/record your voice/etc. Don't let them track your plates, don't ever take your cell phone to the storage facility. Never associate you with that location, or the whole thing unravels.
I could go on and on, but you get the idea.
Our society has become one which actively hunts dissidents. Even if all you want to do is establish a reasonably secure means to express a dissenting opinion online, you should probably consider much or all of the above.
How did we let it get this bad?