Did you know Via Rail has a fleet of British Rail Gauge train cars?
They obtained them from a failed sleeper service through the Chunnel in the 90s. I rode with them on the Montréal to Halifax rail service called The Ocean. Part of a big rail journey I took this summer across eastern Canada and Europe.
I seem to remember reading that there is a heritage railroad society in Canada who runs Swedish passenger cars.
Sweden has a broader loading gauge than mainland Europe (the sleeper services to the continent had to use secondhand German carriages as the domestic ones wouldn’t fit), which would presumably not feel quite as cramped on North American railroads. Britain, however, has an unusually narrow loading gauge. I would imagine that the ex-Eurostar wagons would be considered uncomfortably cramped by Canadian standards.
I remember going on the sleeper train from Berlin to Malmö back in 2011.
It took the ferry between Sassnitz and Trelleborg.
I seem to recall it being normal Swedish SJ sleeper cars, though I do admit that I don't know this for certain
Edit: I think it was either a BC2 or BC4
SJ has had rolling stock in continental gauges for such services. The Stockholm-Berlin sleeper train ran on SJ-branded ex-Deutsche Bahn wagons (which are now RDC-branded, now that the Swedish subsidy has ended).