Mullvad Browser when I’m on my Desktop, which is basically the Tor Browser but without the Tor network. The Mullvad Browser is instead designed to be used with a VPN.
Vanadium when I’m on my phone, which is is a hardened variant of Chromium providing enhanced privacy and security, similar to how GrapheneOS compares to AOSP.
And when I’m at work or using any other computer I try to mainly use Firefox.
Did you even read the post? OP asks for a way to use Instagram as privately as possible while using an account.