

Some VPNs can block trackers in a very narrow sense. If they are set up to prevent DNS leaks and provide an internal DNS service, that can blackhole ads and trackers just like PiHole, Adguard Home, et al.
There’s still a bunch of other ways to fingerprint people online, but I wouldn’t say using a VPN at home offers no benefits.
The study only followed up after 6 weeks, but they noted the group that ate only oats for 2 days still showed positive effects at that time compared to a control group.
Also worth noting that the researchers compared a “2 day oat cleanse” of sorts to a control group of controlled calorie intake, then separately a group who ate oatmeal once a say for 6 weeks compared to a control group that maintained their usual diets. The oatmeal over 6 weeks group stabilized certain metabolic markers but the change wasn’t as drastic as in the 2 day oats only group. Also worth noting that all the subjects had Metabolic Syndrome, so essentially pre-diabetic exhibiting obesity and showing effects from that, so effects on healthy individuals may be different.
To your point about medicine or supplements, the researchers were specifically trying to identify the causal link between oat digestion and cholesterol effects. They posit it has to do with the way the gut biome digests them and chemicals they release. So that could theoretically be put in a supplement form, but the interest is drawn from the fact that oats are generally cheap and widely available. They make for a very good intervention option.