There exist some add-ons that permit to build navigation breadcrumbs, such as NavEE, Construct and Structure.
What could the best way to create HTML navigation breadcrumbs without using an add-on?
Is using multiple conditionals a good choice?
Depending on how your pages are constructed, have you looked at this Tutorial yet?
https://expressionengine.com/learn/smarter-breadcrumbs-with-layout-lists
Russ