Setup page and file list: the lines to check after a paste no longer count the error handling of an action, which is set in its dialog and is not a line of the canvas. Get_Public_Holidays shows 60 lines (64 before), Quick_Try 73 (77 before), the numbers the designer shows.
First public version: the business days between two dates, weekends and holidays left out. The local function Get_Public_Holidays (4 inputs, 3 outputs) reads the public holidays of a country from a public API: France in the sample, another country by changing its ISO code, a region by adding its code. The local function Count_Business_Days (4 inputs, 6 outputs) counts in one Run PowerShell script action. Main adds the days of the company from a CSV file; emptying one setting gives the file alone or the API alone.
Quick_Try does the API call and the count in one block, without the functions. The optional Tests replays 59 cases through Count_Business_Days.
Tested on Power Automate Desktop 2.72.183 on 2026-10-07: five subflows pasted without error; Tests 59 of 59 in 4 min 29 s (51 counts equal to NETWORKDAYS.INTL in Excel, 8 inputs refused with a message); Main gave 247 business days for France in 2026 (11 public holidays from the API, 6 company days from the file) in 21.1 s; the file alone gave 254, the API alone 252, Germany 254, France with Moselle 251; Get_Public_Holidays answered for FR, DE, BE, ES and IT, for the eleven years 2020 to 2030, and refused an unknown country, a year without data, a code in lower case and a date in another format; the quick try pasted into Main gave 252 business days in 13.7 s.
The three header lines of the two functions (# local subflow:, # inputs:, # outputs:) are written in the form of the lab, and the title of region 3 of Count_Business_Days is shorter; comments and titles only, the actions are those of the tested run.