Thank you, this is a solution I have not thought about so far. I tested it and it works nicely. I can now connect the sqlite .db directly to RStudio and can access all my tables and data there. Thank you for this hint, very useful!
For others who are looking for that, the respective R code to access the SQLite.db would be
library(RSQLite)
filename <- "C:/Users/YOUR USER ACCOUNT/OpenForis/Collect/data/rdb/YOUR.db"
sqlite.driver <- dbDriver("SQLite")
db <- dbConnect(sqlite.driver, dbname = filename)
dbListTables(db)
plots <- dbReadTable(db,"plot")
Lutz