Would agree with this about 15-20 years back, but today, you can take 2 bikes that look similar, and only have the shifter clamps & RD bolt being the same spec, everything else may be different.

For the OP, start a list/spreadsheet, list every part from your current bike, and it's spec's, then do the same, compare, and you have your answer as to what is needed, then work out if it's cost effective.