You can use a different launcher to customize your home screen and get rid of the Google search bar. I use Nova and can confirm that a singular Firefox search bar works nicely, and I'm sure that it does with other launchers as well.
I used to really like pixel launcher on my OnePlus phone. I'll get nova a try. Is it just an app. I can't remember how I used to set it up. I know they started discontinuing launchers
You can find the app for the launcher in the play store. There should be instructions in the app for making it your default launcher. Otherwise there are plenty of tutorials online.
So long as you have Firefox installed there's a firefox search bar widget available. In Nova you add widgets with a long press on home screen and swipe up.
I've got android one and was also stuck with the Google search bar.
I'm using lawnchair for years now, works great, is very customizable and opensource. Just put the searchbar you like on the homescreen.
https://lawnchair.app/
Install graphene os. It revomves googles constant tracking and u can still use all ur existing apps. Might take a while to set up but will pay off in the long run in terms of privacy.