Most basic: page numbering on footer

Questions
1

I’ve already browsed al topics, but I’m unable to insert page numbering in my footer. I have this:

#set page(
  numbering: "1",
  number-align: start,
  footer:   
    counter(page).update(1),
    align(left)[
      My Footer
    ], 
    footer-descent: 10% + 15pt,
  )

What is wrong?

2

Try something based on this:

#set page(
  footer:   
    context{counter(page).display()
      [ My Footer]
   }
  )
  This is a page
  #pagebreak()
  This is a page

The important thing here is that context is needed.

The default numbering is “1” and the default alignment is left.

3

Explicit page.footer content needs to explicitly show page number. The set rule does not display page number in any way. Furthermore, the provided example does not compile. Page Function – Typst Documentation

4

Now I’ve set the context, but I want the page number at the location marked by X.

#set page(
  paper: "a4",
  margin: (left: 25mm, right: 70mm, top: 20mm, bottom: 28mm),
  numbering: "1",
  number-align: start,
  footer:   
    context{counter(page).display()
      [X — My Footer]
    #set align(left)
    #set text(10pt)
   },
  footer-descent: 10% + 15pt,
)

Instructions don’t tell anything about a placeholder code for the page number that I can put at X. (Everything would be much easier if we had a placeholder to introduce it in a string.)

5

OK. Now I see. I don’t need a placeholder, because the number is right there at X.
What happens now is I cannot have

   #set align(left)
   #set text(10pt)

It shows an error.

6

# is used in markup mode and not code mode.

7

Let’s leave it here. Thanks anyway.
(It obviously is markup mode. I don’t know what you mean.)

8

You provided a snippet from the page footer, where set rules written in the code mode block, therefore adding # is like forcing to switch to code mode that is already active. Moreover, set rules must go above a styled content. The provided link demonstraits this.