well, you can escape from nether with NO items in hardcore
step 1: find piglins and punch them of a cliff, then they die and drop golden nuggets
step 2: once you got enough gold, trade it with piglins in a 2x2 hole
step 3: repeat steps 1-2 until you have: 10 obsidian, [30% trade chance] and a pickaxe to mine netherack as a support block
step 4: build the portal with 10 blocks and 4 support blocks that u mined earlier, plsce support blocks at the corners
step 5: lure a ghast so he would shot a fireball at the portal and ignite it
TIPS: kill hoglins, they drop raw meat to keep you alive