How to list pages with unnested tags

What I’m trying to do

i want to tidy up my notes and add nestedtags on some pages without them and just having tags
eg. example #wip#wip/write

Manually search for them can be easy via search with "#wip ", but i want to do this to multiple root tags, and i wanna make see how many are they. i want to use dataview because i want to later add more criterias so i can batch select attributes to chooose the nested tags.

But I haven’t been able to isolate the file.etags without nested tags. I tried using list split that can be used to list subfolder on file.folder but it returns error (probably because file.etags are items)

Desired Summary output
Etag Count
#wip 2
#health 1
Desired pages output
Page Etag
[[abc]] #wip
[[abc2]] #wip
#Health
Undesired pages output
Page Etag
[[abc]] #wip
#art/write
[[abc2]] #wip
#Health
[[abc3]] #wip/write

Things I have tried

TABLE length(rows) as count
from "2. Main Topics"
flatten regexreplace( filter(file.etags, (t) => startswith(t, "^#\\w+(^/)($|\s|\b)")), "^(#\\w+)/(\\w+)?", "$1" ) as root_tags
group by root_tags
limit 10
TABLE file.etags
from "2. Main Topics"
WHERE regexmatch(file.etags, "^#\\w+(^/)$")
limit 10