That's a good one, yes!
Here's the story: Code an App that you tried to make mainstream, and you shut it down.
Take snapshots of it, and fill the gap with that portfolio.
Snapshots of past projects are gold. In interviews, i mention the period and also offer to send them pics of the App: an image will fill for 1000 words.
I usually "patch" my gaps in my resume by adding a period in which "I learned new tech, while doing a contract". The tech learned was React, Tessel.io microcontrollers, etc.
In interviews, that "contract was remote", and you can glide over it explaining "why you took some time off to learn these new techs, and how their were needed to expand your knowledge. Hope this helps :)
By "taking time off", i mean you put aside a full time job to make more room for learning with a contract.
Funnily, I spend my daytime researching, reading code, meetings about meetings, gathering requirements.. doing the human interaction aspect. I'll spend a lot of time assembling modules in my mind, while doing the dishes or house chores. By experience, I prefer spending days of hard thinking and hit the keyboard once I know where I'm heading.
Coding is easy, programming an efficient system is hard.
Hey man!.. I'm 53, and I design 3D synthetic worlds with physic simulators in python and C++ for the aeronautic industry. That's on top of still running strong webdev with the latest tech. So yeah, what's your worry?
Snapshots of past projects are gold. In interviews, i mention the period and also offer to send them pics of the App: an image will fill for 1000 words.