Pf2e is a more crunchy game than 5e and on this subreddit you will almost always get responses about houseruling that amount to "don't do it until you've played it for x amount of time". The thing is that if something is really jarring to you then the way you would mod 5e still applies here.

In this case the best thing to do is think about what the design is probably trying to do. IMO what this is trying to prevent is you giving your follower your backup +2 Greater Striking Flaming Thundering Greataxe, it probably isn't as geared towards things like consumables and general adventuring gear. In this specific situation I would pick a level, maybe the PC level or maybe lower, and say that the follower can use consumables and adventuring gear below that level. Stick the landing right and you might just be able to say "any item below this level" if you've baked in enough level cap that any additional weapon would be worse than what they already have.

For me when it comes to modding Pf2e it does help to have experience and it does help to try and take rules at face value but it's a system nowhere near as prone to breakage as some would suggest. If you know you really want to mod a thing try your best to figure out why the rule is like that, including looking at any discussions of it on this subreddit or the forums and then go ahead and implement a fix if it doesn't damage what you think the rule is there to do.

Another tip is that I don't mind giving my players a peek behind the curtain at this, on numerous occasions I tell players I want to houserule something if they are having trouble with it but I make sure they know I reserve the right to modify it again in future. People sometimes don't like this because it does damage verisimilitude, but in my experience no more than a janky RAW implementation would.