Finally, I found an article in Nature from yesteryear, where teflon is thermolyzed at 500°C to yield about 8% trifluoroacetic acid. The high temperatures are needed, as teflon is stable for 2-3 years at ~260°C.
(https://www.thevespiary.org/rhodium/Rhodium/hive/hiveboard/picproxie_docs/000382044-file_kzwo.jpg)
https://www.thevespiary.org/rhodium/Rhodium/pdf/teflon.thermolysis.pdf (https://www.thevespiary.org/rhodium/Rhodium/pdf/teflon.thermolysis.pdf)
I suppose that isolation of the trifluoroacetic acid is best done by bubbling the effluent gases through Na2CO3(aq) as described, then evaporating the water under reduced pressure to get the sodium salt, followed by acidification with H2SO4 and distilling. (TFA bp 71°C, TFA-H2O azeotrope bp 106°C).
The crude trifluoroacetic acid is then purified by allowing it to stand over P2O5 for 12h, followed by 1.5h reflux. Fractional distillation gives the pure material, bp 71°C. Reference: JACS 86, 5445 (1964)
https://www.thevespiary.org/rhodium/Rhodium/pdf/archive/trifluoroacetic.acid.pdf (https://www.thevespiary.org/rhodium/Rhodium/pdf/archive/trifluoroacetic.acid.pdf)