Symbol Characters in Token Symbols (ERC20 and DEXs)

HI all,

As I search for a unique symbol for a token, I notice it seems like very few use wildcard/symbol characters (# { + - $ ! etc.) I assume Solidity doesn't place any restrictions since it treats the symbol as a string. However, I'm concerned with listings (Etherscan, any -swap, etc.) sanitizing the input and thus resulting in no match. (I.e., I assume they're gettinig rid of at least curly braces before doing anything with inputs.) Can anyone comment on or point me to resources that would help me determine how/where symbols like "$$$$" or "_coin_" would be treated by popular swaps / exchanges? Thanks in advance.