Put it another way... On an ADDNODE install you cannot specify the location for the SQL binaries, they always go to the system drive.
I agree it is a good idea to have the binaries on the same drive letters on all nodes, so it is the original primary node you need to fix. My advice is:
a) Fail over to your newly added second node
b) Evict the old first node from the cluster
c) Reinstall Windows on the old primary node
d) Install SQL Server in a configuration to match the other nodes in the cluster
In theory it is possible to uninstall SQL Server on the old primary node and thus avoid the Windows rebuild, but personally I always regard a SQL install as a one-way process because I want the environment it runs in to be as clean as possible.
Original author: https://github.com/SQL-FineBuild/Common/wiki/ 1-click install and best practice configuration of SQL Server 2019, 2017 2016, 2014, 2012, 2008 R2, 2008 and 2005.
When I give food to the poor they call me a saint. When I ask why they are poor they call me a communist - Archbishop Hélder Câmara