I need some java code to make my block emit redstone

I am not 100% sure if anyone here has ready-made code at this moment, including me, this is probably the reason for lack of reply so far

The way to make a block emit redstone is:

   public boolean canProvidePower(BlockState state) {
      return true;
   }
It's power level is this:

public int getWeakPower(BlockState blockState, IBlockReader blockAccess, BlockPos pos, Direction side) {
      return 15;
   }

Put this in your block class and you will have a block that emits redstone power.

I'll experiment and try to find you a way to change the power based on NBT.

I've found a solution.

First make the block a tile entity.

Make a procedure that gives the block a number NBT data. You can call it "MODpowerLevel" or anything else you choose.

Then put this code in your block class:

public int getWeakPower(BlockState blockState, IBlockReader blockAccess, BlockPos pos, Direction side) {
            TileEntity _tileEntity = world.getTileEntity(pos);
            if(_tileEntity != null){
                int _powerLevel = _tileEntity.getTileData().getInt("MODpowerLevel");
            }
            
            return _powerLevel;

The usual power level is a number from 0 to 15; 15 being the amount of blocks powered by a redstone block.

If you change the name of the nbt number data you will have to change the name in the code.

int _powerLevel = _tileEntity.getTileData().getInt("MODpowerLevel"); <- Change MODpowerLevel to your custom name if you want.

I think if the code is in the CustomTileEntity() the world is already provided. You can always use this.getWorld() though.