How to install Debian Linux on a MacBook Pro 13" Mid 2012 for testing (dual boot)? How to back up for case of destroying OS X system?

My MacBook Pro 13" (Mid 2012) is struggling hard with what I'd like it to do (many many open Browser-Tabs, Microsoft Office, Signal Messenger and some more open applications) and I want to test, if Linux might be the better choice for the old machine. Configuration: MacBook Pro 13" Mid 2012 * 2,9 GHz Dual-Core Intel i7 * 16 GB RAM * SSD 870 QVO 1 TB * Intel HD Graphics 4000 1536 MB * Mac OS X 10.15.7 I would like to install Linux (e. g. Debian) for testing without compromising my still running OS X system, so I think I need a Dual Boot solution, right? I don't have experience with the hardware and software topics - bootloader, ... With OS X it was always very easy to boot from another partition or external Firewire HD. **Is there any risk to break my existing OS X system when trying to install Linux (bootloader, ...)?** Usually I would create a disk image of the current system (and data) partition of my OS X on an external hard disk which I could use for a backup later. But I wonder if that is enough. **Do I need to save any other partition or information to get back to the original state in case of failure?** ## EDIT: Storage hardware configuration: *diskutil list internal*

% diskutil list internal                                            
/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *1.0 TB     disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:                 Apple_APFS Container disk2         500.0 GB   disk0s2
   3:                 Apple_APFS Container disk1         500.0 GB   disk0s3
 
/dev/disk1 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +500.0 GB   disk1
                                 Physical Store disk0s3
   1:                APFS Volume Daten                   441.5 GB   disk1s1
 
/dev/disk2 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +500.0 GB   disk2
                                 Physical Store disk0s2
   1:                APFS Volume Ohne Titel - Daten      458.1 GB   disk2s1
   2:                APFS Volume MBP                     11.3 GB    disk2s2
   3:                APFS Volume Preboot                 26.2 MB    disk2s3
   4:                APFS Volume Recovery                526.8 MB   disk2s4
   5:                APFS Volume VM                      5.4 GB     disk2s5

## EDIT 2 - core of my question: p. s. I think my most important question is: could the setup for a Linux+OSX dual boot installation damage something so hard that I would not be able to just boot from an OS X firewire HD, partition the internal SSD and restore a clone (backup) of my working (slow) previous OS X? (It is crucial for me to stay "productive" with this machine and due to a very difficult personal situation I do not have time to fix and repair for some days (and during this time not be able to work with my old OS X, as long as there is no new working system set up.)