After 8 years, today I just deleted all my comments and posts. So far they are deleted. I haven't deleted my account in case I have to delete them again. Fuck spez.
Tested myself. I ran PDS then checked my profile afterwards and everything was gone. I then went to bing and searched site:reddit.com "[USERNAME]" and sure enough, my comments were still there and visible, just not displayed in my profile.
I ran Shreddit last night (the command line tool, not the shitty website). It uses an API key you generate along with your GDPR data export to make sure it gets everything. So far, it looks like it's all gone, but I don't know if Reddit will let it stay gone.