Combine several sheets or files into one table

App and version: {{app_and_version}}
The sources (tab or file names, how many, and whether more will be added): {{sources}}
Whether every source has the same columns in the same order: {{column_match}}
What I will do with the combined table: {{purpose}}

Headers and two sample rows from two of the sources:
"""
{{sample}}
"""

Task:
Show me how to combine these sources into one table in {{app_and_version}} for {{purpose}}, in a way that picks up new rows and new sources with little or no manual work.

Format:
1. Recommended method, with one sentence on why it suits my app and setup. Choose from what the app offers: for example Power Query (Get and Transform) or a VSTACK formula in Excel, or an array in curly braces, QUERY or IMPORTRANGE in Google Sheets.
2. Numbered steps, up to 12, with the app's menu names, or the formula in a code block with every part explained in plain words.
3. A Source column: how to add a column saying which tab or file each row came from, because a combined table is hard to check without it.
4. Mismatched columns: how the method handles a source whose columns differ in name or order, and how to fix it.
5. Blank rows and repeated headers: how to keep them out of the result.
6. Check it: compare the combined row count with the total of the source row counts, and give the formulas for both.
7. Next month: what I do when new data arrives.

Requirements:
- Use only features available in {{app_and_version}}. If the best method is not in my version, say so and give the next best.
- No macros or scripts unless there is no other way.
- Under 450 words, plus formulas.

Example of a check's form only: "Sources: Jan 412 rows, Feb 388, Mar 405, total 1,205. Combined table: 1,205 rows. They match."

If the samples show the sources do not line up, for example a column called "Region" in one and "Area" in another, list the differences before giving the method and ask which name to keep.