For v15, assuming you have a Customer called "ACME Inc" and an Income Account with code "400000" you could do something like: 

customer_name = "ACME Inc"
invoice_ref = "B65253"
invoice_date = "2022-07-01"
invoice_date_due = "2022-07-31"
invoice_line_note = 'Consulting Services'
invoice_line_account = '400000'
invoice_line_amount = '150'
invoice_line_quantity = 10

customer_in_odoo = env['res.partner'].search([('name','=',customer_name)])

if not customer_in_odoo:
  raise UserError("Cannot find Customer!")

invoice_line_account_in_odoo = env['account.account'].search([('code','=',invoice_line_account)])

if not invoice_line_account_in_odoo:
  raise UserError("Cannot find Account for the Invoice Line!")

invoice = env['account.move'].create({
    'move_type': 'out_invoice',
    'invoice_origin': 'External API Demo',
    'partner_id': customer_in_odoo.id,
    'ref': invoice_ref,
    'invoice_date': invoice_date,
    'invoice_date_due': invoice_date_due,
    'invoice_line_ids': [(0,0,{
      'name': invoice_line_note,
      'account_id': invoice_line_account_in_odoo.id,    
      'price_unit': invoice_line_amount,
      'quantity': invoice_line_quantity,
    })],
  })