It is possible to block websites at the browser level, maybe via an add-on. Here, for example, are some recommendations on how to do it in Firefox. [m.wikihow.com
] I've no personal experience, though I do ad-blocking, which is probably effected similarly.
ETA Just had a longer look at that reference. I see that methods 4 and 5 are general phone apps, for iPhones and Androids respectively.
Edited 1 time(s). Last edit was 2019:09:05:16:02:12 by ianr.