Hi and welcome to the forum
Why won't it work on the 2020 spec? Is the pitch of the holes different?
I bought my spacesaver tyre for my wife's new Smart Fortwo last year, as Smart do not have a spacesaver at all, and we will not drive cars without a spare, as 'compressor and goo' kits are not 100% effective that you will get back on the road.
I would usually give you a number of spacesaver companies to try phoning, but as you say you have had problems getting one, I will only quote where I got my Wifes spacesaver from, I have bought a few spacesavers in the past for previous cars from them. Its a Good product.
Here is the Ford Ecosport page for the spacesaver and it quotes 2014 to present, 16" at a cost of £139.95 for tyre + tool kit. What you should do is phone them up and see if it is compatible for 2020, or not. Phone number (0161 302 5656) Good luck, and come back and tell us why 2020 spec is not compatible......
Note a spacesaver is only to get you home or to repair tyre workshop, it is a temporary tyre, and max speed is 50MPH or 80KPH.
https://www.thewheelshop.co.uk/?product_cat=ford-ecosport&filter_vehicle-year=2014-present-day