Quick question about "where/when" they check for transiting Covid related documents. I'm flying from Canada YUL > FRA on AC then FRA > DXB on LH. (Separate tickets - no checked bags)
I suspect I'll need to show proof of Vaccination (and/or test) to satisfy the requirements for transit in FRA And I will also need to show negative test and proof of vac for travel to DXB.

(not totally for this forum) Would this happen at check in at YUL? At the gate for YUL? (For FRA Transit)
Would I need to provide documentation again in FRA at the transfer desk or gate? or will it be on arrival in DXB (at which point i'll pop over to the emirates forum :P)
I'm trying to organize what documents I'll need at what point in transit.

As an aside, for the DXB transit specifically. I suspect LH staff will be vetting my testing certificate somewhere in FRA? DXB seems quite specific on RT-PCR and I'm unsure if my Canadian test only says PCR will I run into any issues? (This maybe a more anecdotal question as I'll endeavour to get the testing facility to print out the appropriate term, but just thought i'd ask)