Combine multiple cells with unique A and different B's into one cell

Goal: combine items that have duplicates in column A and different values in Column B, to get one value of Column A and column B to be a list of unique items in columns B which had duplicate value A as a match.

1. Column A will be the unique value in column D
2. Values in column B will be joined together in column E, for every value in D/A
3. Copy relevant columns to new worksheet with headers
4. Put "=unique(A:A) in D1, and it will autofill column D
5. Put "=TEXTJOIN(",",TRUE,TRANSPOSE(FILTER(B:B,A:A=D2)))" in E2
6. Copy columns D and E, and paste as values.
7. In the original worksheet, use VLOOKUP(A2,NewWorksheet!$D:$E,2,0)
   1. A2 should be the same as columns A/D
   2. This will copy the merged values into the original worksheet
8. Remove the original column B from the original worksheet
9. Use "Remove Duplicates" to remove duplicate rows.