one easy solution - meet at a police station or a very public place. Hard part with zelle or venmo is its possible to get transactions reversed so you really need to be able to trust the person paying you to not reverse the payment.
if it is in person, they could simply just buy btc with the fiat and pay you in btc - that will not be reversed then and you can easily verify the txn on your own.
Or a cashiers/bank check would work also
I had a high school friend sell his truck for 48k via cashiers check 6 months ago… yeah that check was counterfeit and his truck was half way across the country 24 hrs later.
I feel safer using Miner Jones as an escrow (as buyer and seller) and shipping registered mail or priority express with 3rd party insurance. Coin really needs to be authenticated and holo looked at (in general when spending that amount of money). And you need to make sure you are safe as well. When packaged securely and labeled correctly - 99.9% of the time you will be fine. And it will also be cheaper/safer
I couldn’t imagine meeting some guy off the internet with 30k (does Zelle have limits? Venmo was 2k at one time) or a Cas coin