allowedBlocksDependentOnFirstBlock.js

( function() {
	var registerBlockType = wp.blocks.registerBlockType;
	var el = wp.element.createElement;
	var InnerBlocks = wp.editor.InnerBlocks;
	var withSelect = wp.data.withSelect;

	var dataSelector = withSelect( function( select, ownProps ) {
        var getBlockOrder = select( 'core/block-editor' ).getBlockOrder;
		return {
			isFirstBlock: getBlockOrder().indexOf( ownProps.clientId ) === 0,
		};
	} );

	var list1 = [ 'core/image', 'core/list' ];
	var list2 = [ 'core/gallery', 'core/video' ];

	registerBlockType( 'acme/container', {
		title: 'Container',
		icon: 'carrot',
		category: 'common',

		edit: dataSelector( function( props ) {
			return el( 'div', { style: { outline: '1px solid gray', padding: 5 } },
				el( InnerBlocks, {
					allowedBlocks: props.isFirstBlock ? list1 : list2,
				} )
			);
		} ),

		save() {
			return el( 'div', { style: { outline: '1px solid gray', padding: 5 } },
				el( InnerBlocks.Content )
			);
		},
	} );
} )();