Odoo expects you to create the lot on the manufacturing date, so that lot.create_date == manufacturing_date.
There's an OCA module that adds the manufacturing date to the lot, but I'm not certain it changes the calculations to use that new field instead of the create_date

There can be an issue with how Odoo calculates the Expiration date. It uses data / time of lot creation. And not manufacturing end. Let say you create the lot number on manufacturing day one, and the manufacturing process takes 2 days, the expiration date will be calculated on Lot creation date/time, and not Manufacturing end date/time. So dependent on your business process and requirement there might be an issue.
In such a case you should be able to recalculate the expire date (+ best before etc) with an automatic action triggered by the manufacturing order completion.

And btw: There is a field named "Removal date" on the lot, and it seems it is equal to Manufacturing end date (not confirmed).

@Lars Adam
Removal date is the scheduled date at which the lot should be removed from the inventory. Odoo's expiry date are anything but intuitive.
In chronological order, they are:
Alert date, removal date, best before date and expiration date.
Alert date is the date an alert is send to the product responsible to alert that a lot will soon expire.
Removal date is the time the lot should be removed/scrapped
Best before date doesn't have a "hard" meaning, but the docs say that it's for the date the lot starts deteriorating.
Expiry date is the hard date where a product isn't fit for anything. This is the reference date for all the other dates.

When trying to reserve stock for an inventory operation, Odoo will ignore lots past their removal date. They can be manually selected. When trying to consume lots past their expiration date, the user will be warned that they are unfit for usage, but will be allowed to use it still.

@Protovec: What we did is use a standardized lot number sequence. All lots are named YYDDD, where YY are the last 2 digits of the year and DDD is the day of the year (counting from Jan 1st) when the product was manufactured. Using an automation rule, we can calculate the expiration, removal, etc from the lot's name.
Ex: We know that a product has 31 days of lifetime before being unable to be sold. Lot 25001 (mfg'd on Jan 1st, 2025) will then have an expiry date of Feb 1st, 2025 based on its sequence