Digi-Key does have a small selection of Discrete LEDs that do not require an external resistor. Currently there is no way to filter these out in a search, however you will notice this selection here has a 12V Vf (forward Voltage) rating. This is due to an internal resistor that is built into these. If you look at the data sheets they will reference the internal resistor.
Applicable Part Numbers
67-1099-ND 516-1340-ND 4302H5-12V-ND LTH5MM12VFR4600-ND LTH5MM12VFR4100-ND 4302H3-12V-ND 754-2018-ND 4302H1-12V-ND LTH5MM12VFR4700-ND LTH5MM12VFR4400-ND LTH5MM12VFR4500-ND
SSL-LX5093GD-12V HLMP-3601 4302H5-12V LTH5MM12VFR4600 LTH5MM12VFR4100 4302H3-12V L57GGD12V 4302H1-12V LTH5MM12VFR4700 LTH5MM12VFR4400 LTH5MM12VFR4500