Ansible: Access Shell Var in Task - bash

Question

What is the correct way of going about doing this: I have a task with the shell module that exports a var from the Bash shell.
Can I access said var from another task (maybe setting environment?) without having to register command output and parse shellvar_register.stdout?
Does Ansible scope an ansible_env for localhost and remote host?
---
- name: test var play
hosts: localhost
tasks:
- name: export shell var
become: no
local_action: shell export shellvar=foo
args:
executable: /bin/bash
#register: shellvar_register
- name: print debug msg
local_action:
module: debug
msg: "{{ ansible_env.shellvar }}"
% ansible-playbook playbooks/test/test_shellvar.yml
PLAY [test var play] ***
TASK [Gathering Facts] ***
ok: [localhost]
TASK [export shell var] ***
changed: [localhost -> localhost]
TASK [print debug msg] ***
fatal: [localhost]: FAILED! => {"msg": "The task includes an option
with an undefined variable. The error was: 'dict object' has no
attribute
'shellvar'\n\nThe error appears to be in '/home/robert/tmp/common.git
/playbooks/test/test_shellvar.yml': line 12, column 5, but may\nbe
elsewhere in the file depending on the exact syntax problem.\n\nThe
offending line appears to be:\n\n\n - name: print debug msg\n ^
here\n"}
to retry, use: --limit #/home/robert/tmp/common.git/playbooks
/test/test_shellvar.retry
PLAY RECAP ***
localhost: ok=2 changed=1 unreachable=0 failed=1 skipped=0

Answer 1

c.f. https://docs.ansible.com/ansible/latest/user_guide/playbooks_variables.html#registering-variables
Your shell exits when the task is over. Just capture the value as an ansible value for later uses.
- name: set a var
command: 'echo foo'
register: not_a_shell_var
- name: show it
debug:
msg: "{{ not_a_shell_var.stdout }}"

Answer 2

you could use set_fact like in Ansible: Store command's stdout in new variable? and set a new ansible variable, which you can use in other plays too.
- hosts: loc
tasks:
- name: set a ansible variable for later use
set_fact:
new_ansible_var: "foo"
- name: run a command with this var
shell: "shellvar={{ new_ansible_var }} {{ playbook_dir }}/bash_script_using_shellvar.sh"
The first task sets the ansible_variable. The second task takes this variable for shellvar, so the bashscript can use shellvar.