I indeed only have 512GB and discovered the blockchain size the hard way this morning when bitcoind shut down and MacOS complained about disk utilization. I got to 96% ! So close... I'll try out pruned mode today. I ordered an external SSD to download the entire blockchain. I want to study the data and replicate some of the indicators Glassnode developed .
Concerning ZeroMQ & the GUI, I did eventually compile with these flags enabled. Everything seems to work as expected except the GUI. The latter "unexpectedly stops" whenever I try to open it. Anyways, I don't need wallet (or GUI) functionality since I'm only running a node to support the network and study it.
Since you mention studying Bitcoin Core / Bitcoin full node, take note pruned node have few limitation and might hinder you to replicate report by Glassnode. Moving your blockchain files to external storage is better option for you.