I am self-employed and bought a MacBook in Apr '22. Apple allowed me to pay it off in monthly installments interest free over 12-months. How do I deduct equipment costs?

How you deduct the cost of your MacBook depends upon the total cost of the machine.  If it was $2,500 or less, you can elect to take the De Minims Safe Harbor Election, and deduct the entire cost in 2022.  TurboTax will ask you paid for equipment costing $2,500 or less, and give you the option to make the election.  This occurs in the expense section for you business in TurboTax Self-Employed.   If the computer cost more than $2,500 you will have to capitalize it.  You might be  eligible to expense it all in 2022 using Bonus Depreciation or Section 179 Expense.  For more information see the following TurboTax article:

Depreciation of Business Assets