offhand in bedrock mechanics for mobile

Offhand mechanics: block and block - "extra" hotbar slot; block and tool - tool used for breaking, block for placing; Two tools (same, eg two hoes) - Same for the two blocks scenario; two different tools (eg one spear, one hoe) - best tool for block in question is used. By default it can be like an extra hotbar slot. Default is non offhand. For tools