After a successful migration I used a mind map with areas like planning, test execution, and actual migration. It was projected behind me, so people could see the branches. For each area I asked for good and bad points (or points to be improved).
I asked for specific information.
E.g. what do you mean with good tests?
Do you mean that the most important tests were performed?
Were the test cases or test ideas clear for everyone?
For more interaction you could use a flip over with areas and let people place sticky notes on it. After the first round you can sort the sticky notes by stacking them.
E.g. I put “Good communication” on “Implementation plan” after hearing your explanation.
Of course other sticky notes can be added during the process.
In the remote world there are online tools for mind mapping and brainstorming.
My suggestion is to add shorter feedback loops to the test process.
E.g. we are now 3 months later.
At the moment we are doing activities A and B. Are we missing something?
Make an area with two axes:
- how often are we doing this activity? (from sometimes to a lot)
- how much is the impact of this activity? (from low to high)
Next let the participants place sticky notes of activities on the board.
Another opties is to use an area for test activities with two axes:
- Probability - how small or big is the chance, that this feature will fail?
- impact - How small or big is the impact of the failure
Afterwards missing test types or activities can be found using the Testing Quandrants and Heurisk-it cards (see MoT shop).