Can I wipe a smartphone and safely use it to only post political content on public WiFi?

Theres nothing to be gathered from this

Use an aosp rom without any google gapps. You will also need root to have full control over it in order to disable any service you want.

I hear what you're saying but you are playing with fire, seriously reconsider.

you have a phone that is tied to your name and you are posting on pol. why?

Spelling and formatting aside, do you know where you are?

I could reliably trace that phone to you in a month (a week tops in a normal scenario, except OP stated he travels for work which would slow things down). I can determine your entire life, work, friends, relatives, and interests in a month with access to just the metadata, no content, from your emails.

youtube.com/watch?v=kItMfK-Q49Y

I post from my phone,I don't care...

Install linage os and get rid of googleapps

Well, as another possible way to do it, you can find find an illegal immigrant that has access to the internet, and just pay them a few bucks to type whatever you say to them.