How can we filter based on only month and day using queryFilter?

That is not possible out of the box. I suggest to implement a view in database which puts day, month and year into separate columns. Then you can filter on this. In case your data volume is large, consider performance tests.

I'd argue that using an a!queryLogicalExpression() with an "OR" operator and some looping logic could work for this use case, OOB, for a "brute force" approach, assuming there is a finite-and-discernable number of years "back" the query needs to reach (and assuming it's not a large number).

Example:

a!localVariables(
  /* number of years to look back */
  local!numYears: 10,
  
  local!month: 6,
  local!day: 27,
  
  a!queryLogicalExpression(
    operator: "OR",
    filters: {
      a!forEach(
        enumerate(local!numYears),
        
        a!queryFilter(
          field: "myDate",
          operator: "=",
          value: date(
            year(today()) - fv!item,
            local!month,
            local!day
          )
        )
      )
    }
  )
)

result:

I'd argue that using an a!queryLogicalExpression() with an "OR" operator and some looping logic could work for this use case, OOB, for a "brute force" approach, assuming there is a finite-and-discernable number of years "back" the query needs to reach (and assuming it's not a large number).

Example:

a!localVariables(
  /* number of years to look back */
  local!numYears: 10,
  
  local!month: 6,
  local!day: 27,
  
  a!queryLogicalExpression(
    operator: "OR",
    filters: {
      a!forEach(
        enumerate(local!numYears),
        
        a!queryFilter(
          field: "myDate",
          operator: "=",
          value: date(
            year(today()) - fv!item,
            local!month,
            local!day
          )
        )
      )
    }
  )
)

result: