Simply visit pwa.kiwix.org in Chrome / Edge / Samsung Internet / Kiwi Browser, etc., on Android. Read more after the demo:
(please be patient while the demo loads)
See also: [ Install PWA on Firefox for Android ] [ Demo of all OPFS features ]
Chromium browsers (Chrome, Edge, Samsung, etc.) support installing PWAs on Android (as well as on Desktop), and also have large quotas for the Origin Private File System (OPFS). Installing the PWA is wothwhile, because the app runs in its own dedicated session and has its own icon in your Home Screen (or Start menu on Windows). However, you can still use it fully offline just by bookmarking https://pwa.kiwix.org/ in your browser.
File access is much, much faster (approx. 10x faster) for archives in the Origin Private File System than for archives picked from the visible file system. Full-text search also works for archives in the OPFS, whereas access is too slow for that search type to be feasible for other archives. However, for very large archives like full English Wikipedia which won't fit in the OPFS, you can still pick these archives from anywhere on your device, including microSD cards.
See also: [ Install PWA on Firefox for Android ] [ Demo of all OPFS features ]