Mods compatible with Stardew Valley 1.3 are here: https://stardewvalleywiki.com/Modding:SMAPI_compatibility#For_players_.28Stardew_Valley_1.3_beta.29
SMAPI: https://canimod.com/
2 Mods are published:
https://www.nexusmods.com/stardewvalley/mods/820
https://www.nexusmods.com/stardewvalley/mods/824
This wasn't published, but the main idea was that you could cycle the 3 inventory bars while walking around, without having to open your inventory menu.