Have you ever grown comfrey? Per the articles it’s invasive, but the flowers look pretty. Evidently, it’s a “nutritional powerhouse” for deer. Hmmm ... deer food plot with comfrey?
There’s a homesteading page I follow & they just made comfrey salve - something I’d like to try. I’ll have to find a spot & grow some. So now I’m up to elderberry syrup, echinachea tincture & comfrey salve. Add to that ‘fire cider’. I’m going to end up being a regular ‘medicine woman’!
How to Grow Comfrey – So Easy!
https://thehomesteadinghippy.com/how-to-grow-comfrey/
How to Make Comfrey Salve (and Why You Should!)
https://practicalselfreliance.com/comfrey-salve/
How to Make Comfrey Salve For Bumps and Bruises
https://thehomesteadinghippy.com/how-to-make-comfrey-salve/
Homemade Traditional Fire Cider Recipe & Benefits
https://melissaknorris.com/podcast/traditional-fire-cider-recipe-benefits-guide/
Never have cultivated Comfrey. I’ll bet Ellendra has! ;)

Lucky you! ;)
There's different strains/varieties and the invasive one is actually hard to find. Lawrence D Hill of the UK developed Bocking #1-21 but all that's available these days is #4, & #14. #4 can be invasive but not #14.
My goats seem to like it. I had to put fence around the plants.
I have a pretty good comfrey patch going. Mine is true comfrey, which means it can spread by seed. I’m not sure which critter is responsible, but there’s comfrey popping up here and there all over the place now. Which is NOT a complaint! I love the stuff. Thinking about digging up some roots and planting them around the borders of my field.
The more common varieties of comfrey are sterile hybrids, and can only be propagated by cuttings. But, any little piece that breaks off has the potential to become a new plant, so think carefully before you till!
Most comfrey recipes involve oils or salves, but if you were to take a fresh leaf and run it through the blender with some water, you’d get a thick green gel. That gel is absolutely amazing on sunburns, but it loses effectiveness when heated, and preserving it with alcohol or other preservatives means diluting it enough you wonder if it’s worth it. Freezing works best. As for how to filter the gel, you can dilute it some with water until runny enough to strain. I personally prefer it thick, so I use a centrifuge to separate out the solids.
The best sunburn treatment I’ve ever tried is a mix of comfrey and aloe gels, either fresh-squeezed or frozen and thawed.
One of those links you posted warned about comfrey causing irritation if used on an open wound. I’ve never seen that happen, but one danger with comfrey is that it spurs the production of new skin so much, that any foreign material might get trapped inside! This is also why it works wonders on a burn. It doesn’t just soothe the pain, it actually causes the damaged skin to be replaced faster.