This video turned into a huge explanation of how to get started playing the Kalimba. Here are the important sections if you are comfortable with one area and want to skip:

00:04 Step 0: Picking a Beginner's Kalimba
04:35 Step 1: Tuning (if you need it)
06:48 Step 2: Basic Kalimba Techniques
08:24 DON'T FORGET TO DO THIS
08:35 Step 3: Basic Kalimba Practices
12:09 Step 4: Learning Melodies on the Kalimba
18:01 Step 5: Learning Chords on the Kalimba
12:46 Step 6: The Ultimate Kalimba Skill (Next Steps)

Here is the kalimba I am using:
https://amzn.to/3XxvaAF (affiliate link)

Here are some of the resources I mentioned in this video:

Kalimba comparison video:
   • [Sound Comparison] Brahms Lullaby in ...  

These are some Gecko Kalimba models that have at least decent sustain:

K15CAP G Tone
K17CAP B Tone Kalimba
K17CAS B Tone Kalimba
K17R C tone

Tuning app:
https://play.google.com/store/apps/de...

My favorite metronome app:
https://play.google.com/store/apps/de...

Online Piano for tuning (if you don't have a smartphone)
https://www.onlinepianist.com/virtual...