Hi @matt-hyde-s,
Thanks for your comment. I am just back from holidays. I did not try your code yet, but it would not explain why I can install packages from source on my personal laptop [which has R4.3.1], while I cannot install packages from source on my work laptop [which also has R4.3.1].
I think that the core of the problem is not in brms or stan per se, but in my inability to install packages from source on my work laptop.