Recoll has been requested at PA.com before (cf. https://portableapps.com/node/54129) as a possible alternative to DocFetcher (viewtopic.php?t=6202).
At first sight, It appears Recoll is Python based and browsing its FAQ page, I was able to foresee a quick way to turn it natively portable with the help of its '-c' CLI parameter (check the relevant Windows FAQ entry).
As I don't have Paypal anymore and I couldn't find any free version, I was unable to test this -- though it still looked worthwhile posting (see the first quote below) just in case someone else will be able to have a go.
Recoll is a desktop full-text search tool. Recoll finds documents based on their contents as well as their file names.[...] Recoll will index a MS-Word document stored as attachment to an e-mail message inside a Thunderbird folder archived in a ZIP file (and more...). It will also help you search for it with a friendly and powerful interface, and let you open a copy of a PDF at the right page with two clicks. There is little that will remain hidden on your disk.
The port of Recoll to Windows lacks a few goodies like like real-time indexing, or multi-thread execution. Be aware that I ask for a small contribution to download it.
I request a small fee for downloading and using the Windows binary version. I don’t use it myself, so it makes it worth my while (building the thing and its dependencies on Windows is no piece of cake).
According to the homepage, Recoll current version is v1.32.7, released 2022-08-07 (main changelog at https://www.lesbonscomptes.com/recoll/pages/release-history.html).