Hi @Anonymous ,
Do you want to show the percentage based on all the results? Like your example, show the percentage based on 8 results? If so, I did a test on my side, you can refer to my steps:
1. This is my list called “list8”:

2. Go to the app, set OnStart property of App to below. This will create a collection to keep all the results into a one-column- table. Then count the percentage based on this table.
ClearCollect(collist,list8);
ClearCollect(colresults,
Split(Left(Concat(collist,Question1&", "&Question2&", "&Question3&", "&Question4&", "),
Len(Concat(collist,Question1&", "&Question2&", "&Question3&", "&Question4&", "))-2),
", "
));
ClearCollect(colchart,
Table(
{Result:"Agree",Number:CountRows(Filter(colresults,Result="Agree"))/CountRows(colresults)},
{Result:"Disagree",Number:CountRows(Filter(colresults,Result="Disagree"))/CountRows(colresults)},
{Result:"Strongly Agree",Number:CountRows(Filter(colresults,Result="Strongly Agree"))/CountRows(colresults)},
{Result:"Strongly Disagree",Number:CountRows(Filter(colresults,Result="Strongly Disagree"))/CountRows(colresults)}
)
)

3. Add a pie chart, set items property of PieChart control to:
AddColumns(colchart,"percentage",Text(Number*100,"[$-en-GB]##0%"))

4. Set Items property of Legend control to:

5. Open Advanced tab of PieChart control, and select “percentage” option of Labels dropdown:

Check results this time:

If you want to show percentage for each question, you can refer to below steps:
1. Add a dropdown box for selecting question, set its Items to:
["Question1","Question2","Question3","Question4"]

2. Add a button to search the percentage of selected question. Set its OnSelect property to:
ClearCollect(colrecord,
Switch(Dropdown1.SelectedText.Value,
"Question1",Table(
{Result:"Agree",Number:CountRows(Filter(collist,Question1="Agree"))/CountRows(collist)},
{Result:"Disagree",Number:CountRows(Filter(collist,Question1="Disagree"))/CountRows(collist)},
{Result:"Strongly Agree",Number:CountRows(Filter(collist,Question1="Strongly Agree"))/CountRows(collist)},
{Result:"Strongly Disagree",Number:CountRows(Filter(collist,Question1="Strongly Disagree"))/CountRows(collist)}
),
"Question2",Table(
{Result:"Agree",Number:CountRows(Filter(collist,Question2="Agree"))/CountRows(collist)},
{Result:"Disagree",Number:CountRows(Filter(collist,Question2="Disagree"))/CountRows(collist)},
{Result:"Strongly Agree",Number:CountRows(Filter(collist,Question2="Strongly Agree"))/CountRows(collist)},
{Result:"Strongly Disagree",Number:CountRows(Filter(collist,Question2="Strongly Disagree"))/CountRows(collist)}
),
"Question3",Table(
{Result:"Agree",Number:CountRows(Filter(collist,Question3="Agree"))/CountRows(collist)},
{Result:"Disagree",Number:CountRows(Filter(collist,Question3="Disagree"))/CountRows(collist)},
{Result:"Strongly Agree",Number:CountRows(Filter(collist,Question3="Strongly Agree"))/CountRows(collist)},
{Result:"Strongly Disagree",Number:CountRows(Filter(collist,Question3="Strongly Disagree"))/CountRows(collist)}
),
"Question4",Table(
{Result:"Agree",Number:CountRows(Filter(collist,Question4="Agree"))/CountRows(collist)},
{Result:"Disagree",Number:CountRows(Filter(collist,Question4="Disagree"))/CountRows(collist)},
{Result:"Strongly Agree",Number:CountRows(Filter(collist,Question4="Strongly Agree"))/CountRows(collist)},
{Result:"Strongly Disagree",Number:CountRows(Filter(collist,Question4="Strongly Disagree"))/CountRows(collist)}
)
))
3. Add a pie chart, set items property of PieChart control to:
AddColumns(colrecord,"percentage",Text(Number*100,"[$-en-GB]##0%"))
4. Set Items property of Legend control to:
colrecord.Result
5. Open Advanced tab of PieChart control, and select “percentage” option of Labels dropdown:

Check results this time(after selecting a question, must click search to get the results):

Best Regards,
Allen