Help me understand browser isolation

Hi guys,
im trying to understand to what extent are sites isolated on browsers, especially on the mobile space.

To try to limit the ammount of apps in my phone i use Hermit Browser to create what i think is called PWA. I am currently using Amazon,ChatGPT, My City weather site, My region bus and train site and a few others in Hermit.
The good thing about hermit is that it containarizes each site so i feel like im really limiting third party tracking, but Hermit is not OpenSource.

I seems that i can get the same result with just a normal browser. How much are sites isolated/sandboxed from each other within the same browser and profile (i dont think there are profiles on mobile).
If i create PWA with a browser can they see any content of another PWA or other browsing history? The latter is less of a concern since i plan on having a dedicated browser for PWAs.

Could i switch to a browser for my “apps” or should i stick with Hermit? In case should i use chromium or firefox for this. My plan was Brave for PWA and Mull for normal search.

Welcome For a few months I have been using Brave for PWA and Mull for search, as well. Brave for anything I need to log into. Brave breaks for me on a lot of sights because I have hardened it following Privacy Guides. I use Mull Default settings just so I know this is a danger zone.

Here is my notes on Brave Settings which I ganked and edited from privacy guides.

I need to update that I changed “forget me when I close this site”. This is in testing as I mainly use Brave for accounts and PWA.

Brave includes some anti-fingerprinting measures in its Shields feature. We suggest configuring these options globally across all pages that you visit.

Brave shields global defaults

Shields’ options can be downgraded on a per-site basis as needed, but by default we recommend setting the following:

  • Select Aggressive under Block trackers & ads

  • Select Upgrade connections to HTTPS

  • Select Always use secure connections

  • (Optional) Select Block Scripts

  • Select Strict, may break sites under Block fingerprinting

Clear browsing data

  • Select Clear data on exit

Social Media Blocking

  • Uncheck all social media components

Other privacy settings

  • Select Disable non-proxied UDP under WebRTC IP Handling Policy

  • Uncheck Allow sites to check if you have payment methods saved

  • Uncheck IPFS Gateway

  • Select Close tabs on exit

  • Uncheck Allow privacy-preserving product analytics (P3A)

  • Uncheck Automatically send diagnostic reports

  • Uncheck Automatically send daily usage ping to Brave

Brave Sync I do not use Brave sync

Brave Sync allows your browsing data (history, bookmarks, etc.) to be accessible on all your devices without requiring an account and protects it with E2EE.