Typically people who borrower from hard money lenders use single purpose entities. That basically means if the property you are buying is 54 Oakwood Ave, you might make an LLC called 54 Oakwood LLC. For this reason, a hard money lender is underwriting you personally, not the LLC.
Some HMLs don't require tax returns, but why don't you have any? Do you not have any income? Have you just not filed? If you're looking to begin a REI career, having your financials as healthy as possible is a key component. Bridge lenders or banks are going to require your tax returns, so realistically, if you're going to look to hold anything or ever try and leverage yourself with cheaper money, you will need tax returns.
It may be a bit early to get pre approved with a HML. But it's not too early to start putting together a list of HML you'd like to explore working with. Reach out to local networking groups and see what lenders they use. As you get closer to your target start date, I'd inquire about what kind of pre approval programs they have. Most will want to run your credit for a pre approval, so you may want to have narrowed your search down to one HML if you want to get approved. You can always just wait until you have a live deal.
When presenting to a HML, appearances can matter. I'd put together a package to bring them. I'd have my LLC docs, information on the property, a construction budget, and a few comps for the ARV. You'll also want to have an accurate personal financial statement prepared as well. At that point, the lender should be able to give you a very accurate idea of what they want. A lot of applicants I had in the past were incredibly unorganized, so just doing this puts you a leg above the rest.