I have developed a program for two years. - it can mean a 2-year period in the past. Am I right?

Question

Example 1

(1) I have developed a program for two years.

(2) I have been developing a program for two years.

Let's say right now is 2022. So (2) means that the developing of the program is from 2020 to 2022 to now, right?

And (1) can mean the same as (2) but it can also be interpreted as a 2-year period in the past. Am I right?

Example 2

(1) I have drawn a portrait for two years.

(2) I have been drawing a portrait for two years.

Let's say right now is 2022. So (2) means that the drawing of the portrait is from 2020 to 2022 to now, right?

And (1) can mean the same as (2) but it can also be interpreted as a 2-year period in the past. Am I right?

Answer 1

The combination of present perfect with 'for [time]' doesn't sound natural. We can say:

I have developed a program.

I have drawn a portrait.

meaning that my experience of programming/art includes those achievements, but it would be more natural to add which took me two years or similar.

Answer 2

The first Example 1 (1) could more likely be misinterpreted as "I have developed a programme which will last two years". Similarly with Example 2 - "I have drawn a portrait which I will be able to hang on the wall for the next two years".

Were you intending them to refer to the past, you would really need to say: "I spent two years developing a programme" or "I spent two years drawing a portrait".