Virola theidora is certainly a way. But nowadays it seems, it's very very hard to find any good anymore (read many reports of people getting bunk material). Also you have to be aware that it seems, to get it, they usually kill the trees. So from an ecological POV IMHO not an option.
Additionally it is illegal in some countries.
IMHO Pilocarpus Organensis could be another good source but is literally impossible to get.
Bufo certainly seems the "easiest" way, but my morality detector wouldn't allow me to keep them in captivity.
There also seem to be some Acacias which could be interesting. But there the climate could be a problem, as anyways is the case with most of the plants.
That's why I personally now try to go the phalaris way (as it really grows in almost any climate condition). But as it seems that is a very tedious one...(if only there was a seller for "Turkey Red" seeds)
AFAIK there hasn't yet been found a way for an easy separation of 5-MeO-DMT and DMT (although there are some indications that e.g. DMT dissolves better in naphta than 5-MeO-DMT). So if a plant contains both you would have to use a column.
The sublingual way of 69ron is, as I got it, only for low dose application. 69ron didn't like dosing high on 5-MeO-DMT.
But currently it really seems, as has been said, that the 5-MeO-DMT people use is mostly either from Bufo or synthetic.
Any 5-MeO-DMT you can buy online is basically always synthetic. That's quite the opposite to DMT, where it seems most of the DMT sold is MHRB extracted.
And yes, I heard also that it is legal in Canada. But that seems to be a very rare exception nowadays as it is certainly illegal in many countries.
Edit:
E.g. this post from 69ron himself shows that it seems already back then in 2008, finding usable virola was very difficult
(
https://drugs-forum.com/threads/virola-theiodora-resin-dosage-and-5-meo-dmt-content.68192/)
For quite some time SWIM has been attempting to extract 5-MeO-DMT from virola bark with very little success. Apparently, the resin of nearly all the bark he’s obtained was scraped out prior to the bark being put on the market. This is commonplace.