You can break through end portals in survival mode by just pushing a sticky piston with a block through the end portal, lighting the portal and retracting the piston with the block back.
Steps to reproduce:
Craft the ender eyes;
Find a stronghold and it's portal;
Place a block of your choice in the middle of the lava box under the portal;
On top of that block, place a sticky piston facing up; (at this point, the sticky piston should be one single block under the portal)
Place a block of your choice (but no obsidian) on top of the sticky piston; (the block of your choice should be inside, in the center of the portal)
Activate the piston with a lever or some redstone; (the block of your choice should be pushed one block over the end portal)
Light the portal by putting all the eyes in the frames;
Retract the piston; (the block that was on the piston should retract, breaking through the portal)
Break the block that was retracted by the piston, which is currently inside the portal;
->❌ You broke through the end portal and now you got a hole in your end portal!
Video is kinda choppy but i think you can understand the issue from it.
Video: https://drive.google.com/file/d/1iSsg1h_dKEidGMMx1-ZDN2Fe9-iUif-v/view?usp=sharing
I can confirm this on iOS