Sure, here’s an example. I have omitted most of the rows for clarity, hopefully you get the idea:

function wallets_multiadapter_coins_filter( $coins ) {
	$coins['ABC'] = array(

		// Coin symbol
		'symbol' => 'ABC',

		// Coin name
		'name' => 'ABC coin',

		// several rows omitted here

		// URL to an 64x64 icon for the coin. Or leave empty to pull the icon from 'assets/sprites/SYMBOL.png'.
		'icon url' => 'http://www.example.com/abc-coin-icon-64x64.png',
	);

	$coins['XYZ'] = array(

		// Coin symbol
		'symbol' => 'XYZ',

		// Coin name
		'name' => 'XYZ coin',

		// several rows omitted here

		// URL to an 64x64 icon for the coin. Or leave empty to pull the icon from 'assets/sprites/SYMBOL.png'.
		'icon url' => 'http://www.example.com/xyz-coin-icon-64x64.png',
	);

	return $coins;
 }

add_filter( 'wallets_multiadapter_coins', 'wallets_multiadapter_coins_filter' );