Prerequisites
I use several plugins for pass and the tool tomb to be more flexible and secure:
# requisities for pass-import
zypper in python3-setuptools
pip3 install python3-yaml pykeepass
# pass-import
git clone https://github.com/roddhjav/pass-import/
cd pass-import
make
sudo make install  # For OSX: make install PREFIX=/usr/local
# pass-update
git clone https://github.com/roddhjav/pass-update/
cd pass-update
sudo make install  # For OSX: make install PREFIX=/usr/local
# pass-audit
git clone https://github.com/roddhjav/pass-audit/
cd pass-audit
make
sudo make install
# pass-tomb
git clone https://github.com/roddhjav/pass-tomb/
cd pass-tomb
sudo make install
# Tomb
wget https://files.dyne.org/tomb/Tomb-2.7.tar.gz
tar xvfz Tomb-2.7.tar.gz
cd Tomb-2.7
make install
Generate GPG key to open pass
gpg --gen-full-key --expert
(...)
pub   ed25519/0xxxxx 2020-06-09 [SC]
      Key fingerprint = xxxx xxxx xxxx xxxx xxxx  xxxx xxxx xxxx xxxx xxxx
uid                              (Password Store) (Password Store) <xxxx@xxxx.de>
sub   cv25519/0xxxxx 2020-06-09 [E]
Initialize pass and tomb
With the newly created GPG key we create a new tomb and inside this tomb a initialize the passwort store.
# pass tomb gpg-id
pass tomb "Password Store (Password Store) <xxxx@xxxx.de>"
 (*) Your password tomb has been created and opened in /home/dom/.password-store.
 (*) Password store initialized for Password Store (Password Store) <xxxx@xxxx.de>
  .  Your tomb is: /home/dom/.password.tomb
  .  Your tomb key is: /home/dom/.password.tomb.key
  .  You can now use pass as usual.
  .  When finished, close the password tomb using pass close.
Pass is now initialized and created the tombfile with the key itself and the directory ~/.password-store where the tomb with the passwords will be mounted (see code above).
After that we create a git repository with pass to track every change.
pass git init
Initialized empty Git repository in /home/dom/.password-store/.git/
[master (root-commit) 552fb42] Add current contents of password store.
1 file changed, 1 insertion(+)
create mode 100644 .gpg-id
[master ab2a738] Configure git repository for gpg file diff.
1 file changed, 1 insertion(+)
create mode 100644 .gitattributes
You can now add a remote repository if desired to distribute or backup the encrypted password files. I will skip this for now.
Importing passwords from KeePassXC
To import passwords stored in a KeePassXC database I use the tool pass-import:
pass import keepassxc passwords.kdbx
Password for passwords.kdbx:
 (*) Importing passwords from keepassxc to pass
  .  Passwords imported from: dom_private.kdbx
  .  Passwords exported to: /home/dom/.password-store
  .  Number of password imported: 365
  .  Passwords imported:
(...)
After the import is finished your all set and can use pass according to its documentation (man 1 pass).
Auditing your passwords
To audit your stored passwords, pass-audit uses K-anonymity to retrieve the knowledge of breached passwords from HIBP server.
# First open the pass tomb
pass open
# Start the audit process in your home directory
pass audit