Upgrading a crappy experience with a 2TB Fusion Drive on a new 27inch iMac

The issue is the unsatisfactory performance of my new (late 2019) 27inch iMac with it's 2TB Fusion drive. I want to replace this therefore, and have two issues:

1) - This iMac is in use, so I wish to avoid having to do a 'fresh install' of MacOS - I therefore want to clone the 'disc' onto the new hardware, but the Fusion Drive is actually a separate IDE SSD and HDD in some kind of software 'fusion'. So, I would ideally replace the HDD with a SATA SSD, and the existing IDE SSD on the motherboard with a larger/faster SSD.

However, I have no idea how 'transparent' or 'robust' Apple's Fusion Drive arrangement is, in terms of my being able to clone a coherent, single 'disc' from these existing drives, and then repopulate this clone to the new drive(s) once these are installed. This general issue is therefore this 'hardware partition' and True Image's ability to cope robustly with this.

2) - I am also using the existing arrangement with a Bootcamp install of Windows 10. Again, this is in effect another 'partition' of the conceptual single 'Fusion drive' which is in use, and I would wish to clone across 'as one', and would not want to 'break' by doing so. So this general issue is about the 'software partition', and whether True Image can robustly clone and restore a dual operating system.

Further points here:

1) I guess in theory I could use a 2TB IDE SSD to replace the total volume of the present Fusion drive by replacing the motherboard's present 128Gb SSD and clone to this only - if this is possible within True Image?

2) - The fate of the present SATA HDD - to make it a non-MacOS, internal storage disc, or replace it with an SSD, again using it as non-system disc, of faster internal storage. Whether this is possible, and whether something in fimrware or software about the 'Fusion Drive' arrangement needing disabling in some fashion. Or, whether a fast SSD would be worth trying to preserve within the Fusion Drive arrangement, and how to ensure that works without issues.

3) - I also have Parallels installed, so I can access my Bootcamp partition from MacOS. I am aware that Parallels has some ability to also do 'cloning' etc.

4) - Yes, I am aware now I am an idiot for buying this arrangement in the first place!

5) - Yes, I am aware that the replacement of the IDE SSD on the motherboard is an involved procedure, but I am comfortable with this.

6) - Yes, I am aware that the 'speed gain' from swapping the SATA HDD for a fast SSD can be considerable, but IDE M.2 or .NMVE drives do give some multiples of further benefit (I have fitted 64Gb RAM already... ;)