According to Install cmake when nloptr is a dependency · Issue #328 · rstudio/shinyapps-package-dependencies · GitHub a fix has been rolled out so there is a chance that the nloptr issues are fixed now.
And - if nothing works and you just need "a" version of nloptr - downgrading to version 1.x of nloptr (prior of publishing to shinyapps.io) will always fix any compilation issue with nloptr, cf. other post on this topic Installing package nloptr