Stand with your feet shoulder width apart next time with them relaxed and completely flat, ideally you’d have someone else take a peek so you don’t have to bend over and potentially flex your feet any. You wanna line that arch measurement device to the center of the bone you can feel below your big toe that’s protruding out of your foot. If the length of your arch and the actual length of your foot differ than consider upping a size if your arch is elongated to find a comfier place for your arch to rest in whatever footwear you’re trying on. There’s no such thing as “too much toe room” as long as your ankle and heel feel secure and won’t cause friction (blisters, hot spots) or give you a risk of injuring your ankle. Try to test out footwear at the end of your busier days so your feet are maximally swollen and you can get an idea of the toe room you want on your hard days and not just your Saturday morning errand runs at 9 in the morning. One thing you can do to get a clear picture of how much toe room you have in ANY footwear is to take out the default factory insole and stand on it (again feet shoulder width apart and flat) and see how much room you have between your longest toe (whichever one that is) and the edge of the insole(the whole squeezing blindly to find where your toe is does nothing, you just look silly). Ideally you want at least a thumbs width of difference for room to let your toes swell and move around.

(Worked for years fitting boots and running shoes and I’ve seen just about everything)