Maybe:
f6 <- rlang::exprs(a = map(x, ~ mtcars[1:.x, ]),
b = map(x, ~ iris[1:.x, ]),
c = map(x, ~ volcano[1:.x, ]))
mutate(v0, !!! f6)
# # A tibble: 2 x 4
# x a b c
# <dbl> <list> <list> <lis>
# 1 15.0 <data.frame [15 × 11]> <data.frame [15 × 5]> <dbl…
# 2 30.0 <data.frame [30 × 11]> <data.frame [30 × 5]> <dbl…
Unsure about efficiency.
If you want to minimize modifications of existing code and risks of typos, maybe this instead where you just have to replace function(x) list(.... with rlang::exprs(....:
f8 <- rlang::exprs(a = mtcars[1:x, ],
b = iris[1:x, ],
c = volcano[1:x, ])
f9 <- map(f8, ~ rlang::expr(map(x, function(x) !! .x)))
mutate(v0, !!! f9)