There's Petty's Orchard in Melbourne (Templestowe): https://www.manningham.vic.gov.au/venues/pettys-orchard who maintain about 200 varieties of apple.

I have no idea what it's like now, but I went to an open day there years ago and it was incredible. What I learned is there are some extremely ugly Apple varieties that would never get picked up by supermarkets, but tasted unlike anything else I've sampled - literally like candy. Looks like Heritage Fruits still do antique apple tastings periodically: https://www.heritagefruitssociety.org/Antique-Apple-Tastings...

I would love to have a scion or five shipped to Canada, but I doubt the import laws would allow it.

You should contact Tom Brown on his website. He states he's always interested in hearing about a lost apple variety.

What's the variety that is near you?

The Ripponlea Estate in Melbourne has previously hosted heritage apple sales. We grow a Devonshire Quarrenden now and my parents (with more land) took away a bunch of different varieties.