I don't really understand this question. Firefox does support per-site notifications permissions, see https://support.mozilla.org/en-US/kb/firefox-page-info-window#w_permissions

Thanks for replying - I must apologise for not specifying that I am referring to the Android version of Firefox. On a Lenovo tab 10 - Android 6.0.1 under site permissions I can choose either "ask to allow" or block. On the notifications tab I can block or peek. On a Pixel 2 - Android 11 there are the same options for site permissions but the notifications tab offers all Firefox notifications off or on. If on, there's switches for various categories including "site notifications" where I have 22 a day available, only one of which I want from a specific site.

On the Chrome Android browser there's simply a list of all the sites that would like to send notifications, with a switch on each one...

It could well be that I'm missing something obvious but I've not yet found it.

I beg to differ. All the options to which I have referred are obtained by hitting the Firefox settings button and following the available routes. If it is possible to select the blockage of specific sites I would be very pleased to see how it is done. The route that was suggested by TyDraniu only is available on the Windows version.

He says about Firefox Android settings.

Per site permission exceptions can be added:

It's in the three-dot menu drop-down menu under "Settings -> Privacy & Security -> Site Permissions"