In an ideal world, we should be sequencing viruses for each single patient, just like we measure blood pressure.
That does imply that the UK and Netherlands have seen the virus introduced from many sources, which suggests much more widespread transmission than eg New Zealand, which appears to have one lineage.
However, there's probably a huge sampling bias present. Hopefully we can keep doing this sort of genetic lineage testing at greater rates - it's incredibly informative on how it spreads.
For instance, there is a chicken virus (SMAM-1) that unconditionally increases adiposity in the infected bird, even when the chicken is fed the same amount as inunfected chickens. SMAM-1 is zoonotic to humans. It also makes them fat. Several human adenoviruses are suspected of doing similar things. But they have not been studied extensively, because the general prejudice is that people become morbidly obese due to their own lifestyle choices, and therefore excessive adiposity is a condition that should be first-treated with lifestyle intervention, rather than applying evidence-based medicine.
There are still a lot of nonscientific prejudices in general medicine. "Let's sequence all viruses in our patients," sounds a whole lot like "let's wash our hands before touching a new patient, so we don't spread diseases between them," which was once rejected by the experts as implausible hogwash.