There's nothing in matlab to do that with structures, however the newish table type offers all the join functions you need. For outerjoin there are all the options you need to specify left and right keys.
tx = table([1:4]', [2:5]', 'VariableNames', {'A', 'B'}) %note that the data MUST be in columns
ty = table([4:5]', [1:2]', 'Variablenames', {'A', 'C'})
outerjoin(tx, ty, 'MergeKeys', true)
To convert your structures into table
function t = structofvectortotable(s)
s = structfun(@num2cell, s, 'UniformOutput', false); %convert each vector into cell array
c = struct2cell(s); %convert struct into a cell
t = cell2table(vertcat(c{:})', 'VariableNames', fieldnames(s)); %concatenate cells into one array, transpose into column and convert to table
end
