So you are on a hacking/cheat making forum seeking a secondary chat program on a lame chat protocol? OK then. I can't say there are none, or no general purpose cheat finding types hanging around on such places that can also help (you don't always need game/franchise specific stuff) but I generally avoid discord (lame protocol that is best avoided) so pay little attention to it.
Save modding outside of using a save as a further hack (unlikely on the Switch) does not tend to lead to EXP boosts/multipliers unless there is a mechanic inside the game that you can use (some pickup, some bonus mode, some returned to the game after giving it a break type mode). You could edit said save to increase your base EXP (and presumably levels, points and whatever else that goes with that, though some things consider those separate).
Same thing for loot drops and save editing outside of just giving your character said things directly into the inventory or nearby locations.
Not sure what would be causing autowalk and disabled HUD outside of some kind of anti cheat (and given Diablo 1 was somewhat well protected at times though ultimately ruined for many by cheats, 2 was built to handle it a lot better and on PC 3 was online only really in an attempt to reduce it further it seems within reason that something is there, though console is offline so there is that). That could make things more fun to handle than baseline cheat making, which is already a bit more complicated on the Switch compared to other things.
Experience multiplier cheats, outside of the flags/items/whatever mentioned above, tend to happen in one of two ways.
1) The experience added total is found and either the cheat itself does a sneaky little logical shift in whatever direction (logical shift being the binary equivalent of multiplying or dividing by 10, except being binary it is by 2 hence why 99% of such things will be 0.5x,2x,4x,8x,16x,32x,64x.... progressions). This tends to be more for big RPGs that total things at ends of battles but can be other things.
2) You find whatever adds to the experience (presumably by finding the experience total by normal cheat finding means -- whatever you do to find infinite gold/potions/health/... should work for this as well, hopefully you have an easy way of adding exp, might suggest enemy spawners or whatever small action might add even only a couple of xp depending upon your level) and have the game code altered to do it for you. This is what I have seen advocated for thus far on the Switch
https://gbatemp.net/threads/tutorial-1-making-a-multiplier-cheat.603417/ https://gbatemp.net/threads/atmospheres-gdb.602435/ if you wanted a more introductory thing for Switch bothering.
This necessarily sees you have to dip into some light assembly coding, which is a step further than basic cheat making but does it well.
Loot drops probably go via a similar path. Upon either enemy spawn or enemy death (usually going to be death but can be spawn, especially if it can be stolen or is a named enemy with a specific drop range) the calculation for what gets dropped is made. You would want to alter this calculation to be what you want. I don't know what this game will use -- it can be some kind of simple probability (possibly a compound one if modifiers are a thing), can be a random number generator and if it lands in a specific range (which might vary between monsters, even to the point of say common mobs not dropping rare loot at all) then we have a winner and can be some combo of the two. You can usually tell with savestates -- save when an enemy appears, kill them to see the drop, restore savestate, kill again to see drop, repeat, if same after say 15 tries it is likely a spawn thing or the given enemy only drops one thing, if it changes (might be between vendor trash and vendor trash but still different) then more likely on death.
If there is a skill, buff, game feature or equip that increases certain drop rates then can also be keyed in on.
Either way you will probably be starting by finding the enemy health. If it is on spawn then somewhere in whatever writes it will also generate the loot drop, if death then same thing really when the health drops to 0. This means you follow the code backwards or forwards from the relevant point.
Some might find where the spawned item is stored in the game world/level (there will likely be another layer/section for pickups), restore a savestate if they have one or clean up such that the pickups aspect is clean again and then see what goes after killing another enemy. This would also be an easier route to making a cheat that spawns an item at your feet rather than your inventory if you wanted to go that way for some reason (anti cheat might be harder to edit inventory for than it is to spawn on the ground maybe, inventory management concerns with overwriting items, or if there are soulbound things things then that might be a dodge for second players in a group that don't have cheat abilities).
