Using this query as a reference, I found a way to get R to parse the config file as an R expression. My config files now read:
experiments: # Config paths first: !expr 'paste0("C:/Users/",Sys.info(), "/OneDrive/Science/experiments/first")' second: !expr 'paste0("C:/Users/",Sys.info(), "/OneDrive/Science/experiments/second")' third: ...
Then, when I read it in R, I use
config = yaml::read_yaml('base/config.yaml', eval.expr=TRUE) and it works perfectly. It feels like a fragile solution, but so far it’s holding up.