Vector Analysis in QGIS | How to retrieve the centre and corner coordinates of polygons/plots

OSRSGIS
This video is about Vector Analysis in QGIS. I discuss how to deal with misaligned coordinates of field plots and finally demonstrate how to extract the coordinates of plot centre and vertices. The video was motivated by a question I received from a former colleague. See the question below.

The plot is of size 50 x 50 m
Then it is divided into 5 meter grids, from which 5 subplots (a, b, c, d, e; 5 x 5m each) were permanently selected for data collection.
I have the center x, y coordinates (lat, long), and the corner x, y coordinates (AA01, AA10, JJ01, JJ10) of the main 50 x 50 m plot.
Unfortunately, we did not take the coordinates for the subplots.
The question is, knowing the center and corner coordinates of the main plots, is it possible to calculate/estimate the center x, y coordinates of each of the subplot.
I was thinking since I have the corner x, y coordinates, and because I know exactly where the subplots are positioned in each plot, it may be possible to place a lat/lon grid over each virtual plot and extract the GPS positions (x, y center coordinates) of the subplots .
Could that work?
Maybe its even possible to extract the corner coordinates of the subplots as well?