Dear Jonathan,
Thanks for posting the thread on our forum.
Based on your description, I guess that you create a site library like the following. The Subject column is a choice type column with eth choice selections
0: test1, 1: test2, 2: test3, 3: test4, 4: test5, 5: test6, 6: test7, 7: test7, 8: test8, 9: test9, 10: test10, 11: test11, 12: test12.
If yes, I suggest you create a calculated column naming Subject Sort to achieve your requirement. You can type the formula like the following and set the value as number.
=IF(Subject="0: test1",1,IF(Subject="1: test2",2,IF(Subject="2: test3",3,IF(Subject="3: test4",4,IF(Subject="4: test5",5,IF(Subject="5: test6",6,IF(Subject="6: test7",7,IF(Subject="7: test7",8,IF(Subject="8: test8",9,IF(Subject="9: test9",10,IF(Subject="10: test10",11,IF(Subject="11: test11",12,IF(Subject="12: test12",13)))))))))))))
Then group the Subject Sort column and the Subject Column. The view may be showed with some little problem when using the modern SharePoint UI. I suggest you use the classic SharePoint UI. If you want to use some modern web parts on the modern site page, I suggest you use the Embed web part with the code as follows to embed the classic page on a modern page as well.
The modern SharePoint UI.
The classic SharePoint UI.
The embed experience on the modern site page. You can also enable custom script in SharePoint Online Management Shell with the command
Set-SPOsite <SiteURL> -DenyAddAndCustomizePages 0 and insert the code as follows to hide the left navigation bar to make the classic page look better.
<style type="text/css">
#s4-ribbonrow, .ms-cui-topBar2, .s4-notdlg, .s4-pr s4-ribbonrowhidetitle, .s4-notdlg noindex, #ms-cui-ribbonTopBars, #s4-titlerow, #s4-pr s4-notdlg s4-titlerowhidetitle, #s4-leftpanel-content {display:normal !important;}
.s4-ca {margin-left:0px !important; margin-right:0px !important;}
.ms-core-navigation { display: none; }
#contentBox { margin-left: 0; }
</style>
The embed code is like the following.
<iframe width="100%" height="500" src="xxx"></iframe>
Best Regards,
Cliff