rPackages on ubuntu fail to install (uname related ?)

My first time trying to get R packages with nix (2.3.4, installed via apt) on ubuntu (20.10) and I get a similar error for several packages:

teto$ nix-build -A rPackages.clipr channel:nixos-unstable
warning: Nix search path entry '/nix/var/nix/profiles/per-user/teto/channels' does not exist, ignoring
these derivations will be built:
  /nix/store/fwnqana9qlbxc5gdmf1z86mlr1ymyk3a-r-clipr-0.7.0.drv
building '/nix/store/fwnqana9qlbxc5gdmf1z86mlr1ymyk3a-r-clipr-0.7.0.drv'...
unpacking sources
unpacking source archive /nix/store/qzarlhd0sqknxgi7b7skv8l2v89jyb50-clipr_0.7.0.tar.gz
source root is clipr
setting SOURCE_DATE_EPOCH to timestamp 1563858003 of file clipr/MD5
patching sources
configuring
building
running tests
installing
Error: package or namespace load failed for 'utils':
 .onLoad failed in loadNamespace() for 'utils', details:
  call: system(paste(which, shQuote(names[i])), intern = TRUE, ignore.stderr = TRUE)
  error: cannot popen '/nix/store/nsqal2vl76faah1hs5i8h8glzhlidbp7-which-2.21/bin/which 'uname' 2>/dev/null', probable reason 'Cannot allocate memory'
Error: package or namespace load failed for 'stats':
 .onLoad failed in loadNamespace() for 'utils', details:
  call: system(paste(which, shQuote(names[i])), intern = TRUE, ignore.stderr = TRUE)
  error: cannot popen '/nix/store/nsqal2vl76faah1hs5i8h8glzhlidbp7-which-2.21/bin/which 'uname' 2>/dev/null', probable reason 'Cannot allocate memory'
During startup - Warning messages:
1: package 'utils' in options("defaultPackages") was not found
2: package 'stats' in options("defaultPackages") was not found
* installing *source* package 'clipr' ...
** package 'clipr' successfully unpacked and MD5 sums checked
** using staged installation
Error : .onLoad failed in loadNamespace() for 'utils', details:
  call: system(paste(which, shQuote(names[i])), intern = TRUE, ignore.stderr = TRUE)
  error: cannot popen '/nix/store/nsqal2vl76faah1hs5i8h8glzhlidbp7-which-2.21/bin/which 'uname' 2>/dev/null', probable reason 'Cannot allocate memory'
ERROR: installing package DESCRIPTION failed for package 'clipr'
* removing '/nix/store/fyhjnz3wb5qh893k9m5gq6y95aiakw6v-r-clipr-0.7.0/library/clipr'
Warning in q("no", status = status, runLast = FALSE) :
  system call failed: No such file orteto@mcoudron:~/nova/nova-nix$ nix-build -A rPackages.clipr channel:nixos-unstable
warning: Nix search path entry '/nix/var/nix/profiles/per-user/teto/channels' does not exist, ignoring
these derivations will be built:
  /nix/store/fwnqana9qlbxc5gdmf1z86mlr1ymyk3a-r-clipr-0.7.0.drv
building '/nix/store/fwnqana9qlbxc5gdmf1z86mlr1ymyk3a-r-clipr-0.7.0.drv'...
unpacking sources
unpacking source archive /nix/store/qzarlhd0sqknxgi7b7skv8l2v89jyb50-clipr_0.7.0.tar.gz
source root is clipr
setting SOURCE_DATE_EPOCH to timestamp 1563858003 of file clipr/MD5
patching sources
configuring
building
running tests
installing
Error: package or namespace load failed for 'utils':
 .onLoad failed in loadNamespace() for 'utils', details:
  call: system(paste(which, shQuote(names[i])), intern = TRUE, ignore.stderr = TRUE)
  error: cannot popen '/nix/store/nsqal2vl76faah1hs5i8h8glzhlidbp7-which-2.21/bin/which 'uname' 2>/dev/null', probable reason 'Cannot allocate memory'
Error: package or namespace load failed for 'stats':
 .onLoad failed in loadNamespace() for 'utils', details:
  call: system(paste(which, shQuote(names[i])), intern = TRUE, ignore.stderr = TRUE)
  error: cannot popen '/nix/store/nsqal2vl76faah1hs5i8h8glzhlidbp7-which-2.21/bin/which 'uname' 2>/dev/null', probable reason 'Cannot allocate memory'
During startup - Warning messages:
1: package 'utils' in options("defaultPackages") was not found
2: package 'stats' in options("defaultPackages") was not found
* installing *source* package 'clipr' ...
** package 'clipr' successfully unpacked and MD5 sums checked
** using staged installation
Error : .onLoad failed in loadNamespace() for 'utils', details:
  call: system(paste(which, shQuote(names[i])), intern = TRUE, ignore.stderr = TRUE)
  error: cannot popen '/nix/store/nsqal2vl76faah1hs5i8h8glzhlidbp7-which-2.21/bin/which 'uname' 2>/dev/null', probable reason 'Cannot allocate memory'
ERROR: installing package DESCRIPTION failed for package 'clipr'
* removing '/nix/store/fyhjnz3wb5qh893k9m5gq6y95aiakw6v-r-clipr-0.7.0/library/clipr'
Warning in q("no", status = status, runLast = FALSE) :
  system call failed: No such file or directory
builder for '/nix/store/fwnqana9qlbxc5gdmf1z86mlr1ymyk3a-r-clipr-0.7.0.drv' failed with exit code 1
error: build of '/nix/store/fwnqana9qlbxc5gdmf1z86mlr1ymyk3a-r-clipr-0.7.0.drv' failed
 directory
builder for '/nix/store/fwnqana9qlbxc5gdmf1z86mlr1ymyk3a-r-clipr-0.7.0.drv' failed with exit code 1
error: build of '/nix/store/fwnqana9qlbxc5gdmf1z86mlr1ymyk3a-r-clipr-0.7.0.drv' failed

I tried increasing the memory but what seems to have solved it is disabling the sandbox. It does seem wrong though.