If you don't use any identifiable information for the account (i.e email, post any photos with your face, or real name, that you use for anythinh else), use a VPN, an anti-fingerprinting browser like Mullvad, and most importantly use IG just for DM and nothing else, you should be pretty ok. Just the people you talk to (and what you talk about) will give them plenty of data, tho.
One way to avoid having to use the website or their apps at all is to run your own Matrix server with meta-bridge, which can bridge Messenger (and I think even IG DMs, never tried that tho), so you minimize the contact surface you have with their site, because you are chatting through an unrelated app.
If you don't do most of that, Meta already has a shadow profile on you anyway, since they track stuff across websites based on numerous fingerprinting methods. I never really looked into it, but AFAIK most of websites have the "FB like" widget that Meta uses to track people across the internet, and I'd guess that Meta is pretty good at working with that data.
Not sure about directly poisoning the analytics, but you could just run something like a VM with a pyton script with Selenium that just randomly browses web or IG.
