The original overview was no longer relevant, as I published my farm cave mods. I will say that I decided to change the packs (explained more below) to work with a wider range of play styles.

15 Oct 2023: Added packs for Wild Food and Pixie Forage by WildFlower. Comes in allYear, offYear, and seasonal formats. Of Note: Fall and Winter spawn in seasonal pack with have very few fruit spawning. 
I was debating on whether or not I should add Wild Food, as there are only 4 fruits in the mod, but I figured that if players are using one mod then they're probably using the other so I included it anyway. With that being said, if you only play with Wild Food then you will not see a lot of variety in your spawns.
31 Dec 2022: Added packs for Hybrid Fruit Trees. Comes in allYear, offYear, and seasonal formats. Of Note: seasonal pack will not have any fruit spawn during the winter, while offYear pack will have all fruits spawn during winter (as well as in their off seasons).
28 May 2022: Fixed a typo in StardewVineyard's manifest.
Big changes were made!

• Went back to the original way fruits spawned in version 1.0.0 as it seems that most people were having more success with it when using most modded farm cave mods. I archived the 1.0.1 versions so there wouldn't be any confusion. If fruits spawn out of bounds, please use a mod like Noclip Mode mod to access them.
• Changed the spawn rates, especially of the Vanilla mod pack. Since there are a lot of players who want to use these mods with smaller sized farm caves, the spawn rates have been rebalanced and standardised.
• Added new fruits to Raffadax and Magic Tree Roots. Removed discontinued fruits and some accidentally added veggies (side-eyes White Alpine Strawberries)
• For big mods- like Raffadax, PPJA, Odditrees, etc.-, the zipped file contains 3 different packs featuring 3 different spawn rates: allYear, offSeason, and seasonal. allYear spawns all fruits, regardless of season, with a chance of 3-8 fruit per day, and it resets after 2 days. offSeason spawns fruits out of their harvest season* with a chance of 2-5 fruits per day, resetting after 4 days. seasonal spawns fruits during their harvest season* with a chance of 1-3 spawning per day, resetting after 7 days.
  
  
  
  • The Vanilla mod pack is split this way.
    
  • You CAN play with all three types without issue. Or you can simply pick one (or two) and drag them into your mod folder.
    
  • There is a readme file included in all of these downloads that explain the differences, for your convenience.
    
  • *Some fruits (especially in StardewVineyard) have two growing seasons, so fruits either won't spawn during both seasons in offSeason OR will spawn for two seasons in seasonal.
    
• For smaller mod packs (RareCrops, SSaturn, etc) there is only one pack in the download, all fruits spawn all year with a chance of 2-4 spawning per day. Resets every 3 days.
  

Of note, even though the spawn rates and/or reset times have shortened in most cases, this STILL increases the spawn rate by a lot, as the chance will never be 0 (ie, skip days) AND will still fill your cave if you install/use more than one pack. If you would like the spawn rate to be higher or to increase the time in-between resets, simply edit the content.json to your liking :)

Fruits will appear every day, alongside regular fruit spawn in fruit caves. Fruits will spawn in mushroom farm caves as well.
There are separate packs that include popular JA/DGA added fruit that can all be used together. A fair warning, be very vigilant if installing all of these packs, as caves will fill rapidly.
The Vanilla version is compatible with SDV 1.4 aka mobile version. Other mods should be compatible with SDV 1.4 (unless their manifest explicitly states otherwise, but I do not think so). However, even if you do not have some of the fruits in the packs, you will only get low level debug messages and the fruits you do have will still spawn in the cave! :D
Current Compatibility Packs:

• PPJA's Fruits and Veggies plus PPJA's More Trees; DGA and JA versions available.
• Bonster's Crops
• Bonster's Oddi-Trees
• Bonster's Rare Crops (Oddi-Trees); Separated cause oddi-trees is massive
• SSaturn's Tropical Farm
• Stardew Vineyard
• Raffadax Teas and Trees
• Magic Tree Roots
• Ahegao Dryads: NSFW
• Hybid Fruit Trees [NEW as of 31 Dec 2022]
  

Note: You do NOT need to have Vanilla Pack installed in order for fruits to show up! Each pack can be installed separately and still work.
I will happily make more packs, but packs should have at least 5 fruits (emphasis on FRUITS) in order for me to include them as a separate pack.

Extract zipped files and place content in your Mods folder.

To uninstall, simply remove my mod.

Any mods that increase the size of the Farm Cave significantly. Vanilla Farm cave is so tiny, that it will fill up extremely fast.
Hippo's Farm Cave Variety by acearohippo (aka me)
Hippo's Cliffside Falls Farm Cave by acearohippo (still me)

Configureable Farm Cave Extension by BoogieBest.

Esca's Farm Type Manager for, once again, coming in clutch. Esca for helping me get the DGA version of PPJA to work!