Is there any compact relay (or any high current) chip for Raspberry PI?
I'd suggest a low-side transistor array, such as the ULN2803A "Darlington Transistor Arrays" to get eight channels per package. With 500 mA per channel it is perfectly suited to directly drive small relays. Note that this is the absolute maximum rating. If using all channels simultaneously the total substrate-terminal current of 2.5 A is limiting here. So a reasonable maximum is 300 mA per channel. Be advised that at this current the collector-emitter saturation voltage leads to worst case power dissipation of 3.8 W.

Somewhere burried deep in the data sheet it is suggested that it works with 3.3 V logic levels as provided by the Raspberries GPIO pins.