Help first time wearing potential issues

Hi all

Jut purchased my first pair of barefoot shoes - Lems Primal Zen shoes. I’m a little bit concerned on first wear as when walking I can feel my toes or toenails (which need cutting lol) touching the end/front of the shoe , just for everyone’s information I printed the official Lems shoe size guide and stood on it to get the correct fit (US 9.5) , however they feel slightly small in person - maybe compared to what I’m used to. They did say the Lems come undersized compared to normal shoe size (my normal size is 10-10.5 US). I’m concerned about my toes touching or toenails when walking, or is this a break in thing? Or should I return for a size up even though the size guide says these ones will suit?

Has anyone had a similar experience with this brand or others?

Thanks for any information