Alan, I tend to keep an eye on the Install Lazarus on Linux pages and recently made some updates to the Mac page. While I see your point with having separate pages for every platform combination, I don't think its a good idea.
Using the Linux page as an example, I discourage people from making a new page for every linux distribution, even, in some cases, each version of every distribution ! It leads to far too many unmaintained pages and its not a good look when someone googles for "installing lazarus on Linux" and gets a page that tells them to run "apt-get install lazarus" on a Ubuntu 14.04 box !
In the case of the Mac page, just how different is the process on Apple Silicon ? I personally have no idea but if its broadly similar, a single page covering all MacOS is likely to get a lot more love and care than one devoted to a single point in time and space.
But, as you know Alan, the Wiki is open to everyone (after a very easy test to get in initially). If you think a new page is needed, its up to you, as an Apple Silicon owner, to make it ! Or, your choice, add what you have recently learnt to the existing page. Those who come after you will be grateful which ever way you choose to go.
Davo