In Australia, it’s common to shorten names, then add:

• “-o” suffix to names ending with a consonant sound. Thus, David>Dave>Davo, Steven>Steve>Stevo, John>Johnno, Dominique>Dom>Dommo
• “-az” or “-azza” to names ending with, or containing, an “ar” syllable. Gary>Gaz or Gazza, Sharon>Shaz or Shazza, Barry>Bazza
• ”-ie” (“ee” sound) to names ending with a vowel sound (but sometimes with consonant sound too). Stuart>Stew>Stewie, Frank>Frankie, Don>Donnie

The UK had a history of rhyming nicknames for shortened versions, like William -> Will -> Bill, and most of those are still common in English speaking countries. Richard -> Dick, Robert -> Bob (also Hob, Dob and Nob but these didn't survive).

These shortened versions can then get extended: Edward -> Ed -> Ted -> Teddy, Margaret -> Meg -> Peg -> Peggy, Anne -> Nan -> Nancy

In the middle ages it was common to make a diminutive name by adding -kin, -in, or -cock, which gave us John -> Jankin/Jenkin -> Jakin -> Jack. Also, Robert -> Robin, Henry -> Hank

• Pepe for José
• Pancho for Francisco
• Nando for Fernando
• Quique for Henrique
• Nico for Nicolás
• Cris for Cristian[o]
• Bea for Beatríz
• Leti for Leticia
• ...

• Fredi or fredy for alfred
• Hampi for Hans-Peter

Not technically an answer but perhaps the absence is surprising / of interest to someone:

We don't typically do this in the Netherlands. I find it very strange to call someone something that isn't their name (or at least a part thereof if the parents chose something unwieldy), especially to the point where a culture develops a set of default secondary names based on their real first name. Mostly obvious ones but sometimes also entirely unguessable. I learned this is a thing in other countries from my German partner

We do have birth names (some biblical crap, like the holy Johannes for someone called Jo) but it's not like they'd ever introduce themselves to anyone as such (not even when meeting the king). It's not their name, their parent doesn't say it when they've done something wrong, and I doubt they'd respond to it if it's not super obvious from other clues that you mean them. It's just there for ceremonies at church altars and airport terminals

Pancho, Paco, Pacho, isco, Francis, Fran for Francisco

Tano for Santiago

Cheo, Pepé, Chepe, Jose (different pronunciation) for José