"Find on page" for webarchive files

I store many .webarchive research documents, and finally try to buy DTTG to search on the go.
From there I learned that I cannot do what safari call “Find on page” in file for .webarchive files, like I can do on PDF files.

I only use DT and DTTG for PDFs and webarchive, so I don’t know whether this issue also happens on other file formats.

I noticed that there is post from 3 years ago addressing same issue but for markdown & rich text documents (cannot make reference as discourse limit me to not include links)
discourse (dot) devontechnologies (dot) com/t/cannot-search-plain-text-or-markdown/22855

please add this capability, or if it already exist, please tell me on how to do it. thank you!

Slightly off-topic: You might want to consider that Apple has deprecated webarchives. There’s been a thread about this in the DT forum some days ago.