Route around it by not depending on Substack at all and moving the content to a place you actually control... for what it’s worth, Blogsitefy is something I built that lets you turn Google Docs into a blog on your own domain so platforms and age‑gate policies can’t lock you out in the first place.
Build your own
VPN from a different country
This is always going to be the simplest answer until VPNs start being regulated or blocked, or there's some mandatory BS age gate in every country worldwide. Which hopefully will be never.
Already tried that. Both from my home IP in Canada and from a commercial VPN service exiting in Canada and the US. No joy.