Plain <select> element vs Bootstrap's dropdown element rendered on mobile device

Answer 1

DevTools Device Mode does not emulate mobile-specific UA handling of form elements. This is actually very tricky to do since those things are compiled for that platform build.

The best thing to do is know there will be a difference. In the case of select elements it really doesn't matter much. Since the mobile UX is a full screen scroll selector of the choices.

The absolute best thing, as always, is use Device Mode as a guideline. It is not absolute nor can it be. You will always need to do on-device testing to verify everything works as expected. DM simply gets you 85-90% of the way there without issue.