Recently I have found some computers on which, due to their performance, no superior operating system can run. For all those who are in the same situation or who simply want to use Windows XP for nostalgia or on a VM, I leave you the list of all (or almost) the browsers you can install.
Updated (you can visit practically all the sites)
1) 360 CHROME BROWSER (Based on Chrome 78) https://browser.360.cn/ee/
2) Maxthon 5 (Based on Explorer with Chrome engine) https://www.maxthon.com/mx5/
3) New Moon (Based on PaleMoon/Firefox) http://rtfreesoft.blogspot.com/search/label/browser
Updated (but all not sites working correctly)
4) K-Meleon Browser (Based on Explorer, some sites like WhatsApp Web and Google Meet don't work) http://kmeleonbrowser.org/download.php
5) MyPal (Based on PaleMoon 28x) https://github.com/Feodor2/Mypal/releases
Not updated (famous browsers, not all sites working correctly)
6) Chrome 49 (The latest version for WinXP) https://www.slimjet.com/chrome/google-chrome-old-version.php
7) Chrome 33 (For processor without SSE2) https://www.hwupgrade.it/download/scarica/4939/15/
8) Firefox 52 (The latest version for WinXP) https://download-installer.cdn.mozilla.net/pub/firefox/releases/52.9.0esr/win32/it/
9) Opera (Not recommended) https://www.opera.com/en/download