Yes, you could use something like this:
The preference for a bus-bar comes from a number of factors, reliability is one, the other is most MCB can only take 25mm total conductor, so you could not loop in and out cable for 100A as needed in a CU. But reliability/safety from a good connection is reason #1
https://www.NoLinkingToThis/p/wylex-ese2-ip40-2-module-unpopulated-din-enclosure/32311
But you would need to allow for earthing the metalwork (no idea if it has a terminal strip inside or not) and you could use Wago for joining the neutrals. Not ideal, but if that is all the space you have...The preference for a bus-bar comes from a number of factors, reliability is one, the other is most MCB can only take 25mm total conductor, so you could not loop in and out cable for 100A as needed in a CU. But reliability/safety from a good connection is reason #1