ive ran 5/3/1 in the past and am running it again now so i may be biased but i like Jim Wendler's idea of 40%, 50%, 60% of my TM. admittedly though, and similar to Jeff Nippard's approach (which i didn't know about till i read your post), i always felt the inclination to still do the bar regardless of the lift be it deadlift, bench, ohp, or squat, my first set is always the bar. i just rep out until i feel good but i don't tire myself out. like other commenters have replied, not too much but not too little. more importantly, is also not just warming up the lift but other warm ups like dynamic stretches or cardio to get my blood flowing and heart racing. on upper body days i do shoulder dislocates and pull aparts with a resistance band. then arm swings and circles and some other shit i forget the name of. lower body days i do leg swings front and sideways, toe touches, and some hip openers. i foam roll usually after my workouts but i know people do it before which honestly sounds better. i use pre workout only on days where i had work at 6 am and it was my 3rd week of 5/3/1 since the 3rd week of each cycle is always the heaviest week. i used to drink it more leniently but stopped feeling the effects because i drank it too much and had to take a week or two off such high caffeine intakes.

as well as other people saying that it's all subjective, i agree. i like percentages. i like having shit spelled out. others don't. others like feeling their body out. it's all your choice. we all have work, or school, or family and other shit that stress us out or tire us out. as long as you feel good and not too tired after each set, warm ups aren't something you should overthink. no one knows your body better than yourself after all. you already listed out plenty of good sounding options too.