This is a two step process.   

First: devalue the Current Asset to $0 and transfer the value to your Fixed Asset account.

By devaluing the product to $0, you are removing the value from your Inventory (keeping the item so you can move it around the company and keep track of the current location).  The counterpart is the Fixed Assets account, which will show on your Balance Sheet. 

Next: define the depreciation schedule of the amount to create a running Fixed Asset.

By defining the depreciation schedule, you will start to see the value depreciate over time, reducing the value on your Balance sheet by moving portions of the value to depreciation expense on your Profit and Loss statement.

Note: You can only do this for Products within a Category defined with a Costing Method (ie: not standard cost) and Automated Inventory valuation.

Steps:

A. Via Inventory --> Reporting --> Valuation, find the product you want to Capitalize and select it. From the ACTION Menu, select Adjust Valuation to open the Add Manual Valuation Wizard:

B. In Added Value, enter the entire amount of the product(s) but with a negative sign, to indicate you are de-valuing the current asset value to $0.

Note: In this example, our finished product was worth $10,000 based on the Bill of Materials and other construction costs.

C. Open the Journal Items Menu, view entries in the Fixed Asset Account, find the entry just created (use the Product to filter). Select it and click Create Asset.

D. Define the depreciation parameters, and create the Asset following the standard process documented at https://www.odoo.com/documentation/18.0/applications/finance/accounting/vendor_bills/assets.html#assets-entries

You will then have the same functionality and reporting capabilities as if you had created the Fixed Asset via a Vendor Bill (Fixed Assets you buy).