When you said "only the most expensive", I got concerned. Then I went to the website (https://cyclopure.com/product-category/store/), and see the countertop Purefast cartridge is $40-45. So I wonder what you are actually finding problematic here?
From your first link. second paragraph: "“These $45 filters can provide up to 65 gallons of PFAS-free water, replacing 700 single-use water bottles,” said CycloPure chief executive officer Frank Cassou. The cartridges will be available in early April 2022."
Agreed, they are more expensive. Are they the most expensive? No. Do you have a better short term alternative? One option would be to use distillation. It would be lovely to remove PFAS entirely from the planet, but that isn't happening in the short term, unless you are aware of something I'm not. Please share? I'm just trying to find ways to reduce the toxic load for myself and others. Thanks!
Here is EWG's article on the topic, which gives similar recommendations: https://www.ewg.org/research/getting-forever-chemicals-out-drinking-water-ewgs-guide-pfas-water-filters