In this case, a pixel 5a5g with GrapheneOS. I use my phone as an additional backup location for all the various files on my laptop. I have yet to set the fingerprint sensor, because I don’t trust them, but I always make sure to set an eight digit pin screen lock before leaving the house. Now say I went out with my phone in this state and lost it. Anyone who found it, I realize, with evil intentions would probably just want to wipe it and sell it. But even so, how hard would it be for them to access the private data on my phone in a situation like this?
The question is always going to be “who are you defending against?”
If the CIA/FBI/MI5/KGB etc want in to your data, they’ll probably find a way. If it is just stolen, then the phone’s built in protection is going to stop anyone from brute forcing it.
But your biggest weakness is yourself. Do you really want to type in a 8 digit pin every time? No. So you’ll leave it unlocked for longer - which gives a theif more time to fiddle with it.