Update: When being careful and not purging any KDE/GNOME "central" packages, plus checking the suggested purging solutions before committing, it seems to go fairly well purging ca 1.5GB worth of programs. It turns out that several of the problems encountered upon remastering 7.0.2-7.0.5, disappear if I write /home + /var to the new persistent image, taking up a few hundred megabytes there. I don't know what this is, maybe something with aufs - but at least it now seems to work like it used to before. One should note that this isn't that much of a loss in practice, as /var will be populated with apt data as soon as we start updating and installing packages. When these data are already written to persistent store in the remastering process, updating will not take som much extra space.
Fanxiang SSD 4TB 2TB 1TB PS5 SSD M.2 NVME SSD 7300MBS PCIe 4.0 Solid State Drive
$269.99
Fanxiang 4TB 2TB 1TB SSD 550MB/s 2.5'' SATA III Internal Solid State Drive lot
$188.99
Netac 1TB 2TB 512GB Internal SSD 2.5'' SATA III 6Gb/s Solid State Drive lot
$119.99
Kingshark M.2 2242 2280 SSD 128GB 256GB 512GB 1TB Internal Solid State Drive Lot
$179.99
Patriot P210 128GB 256GB 512GB 1TB 2TB 2.5" SATA 3 6GB/s Internal SSD PC/MAC Lot
$15.50
WD BLUE 3D NAND 250GB 2.5" SATA Laptop SSD Solid State Tested,Wiped -WDS250G2B0A
$16.00
Western Digital 256GB M.2 PCIe NVMe SSD PC SN740 M.2 2280 SDDPNQD-256G-1006
$16.99
Patriot P300 128G 256GB 512GB 1TB 2TB M.2 2280 PCIe Gen3x4 NVMe Internal SSD Lot
$16.99
Fanxiang M.2 SATA SSD 2TB 1TB 512GB 256GB SSD Internal M2 Solid State Drive Lot
$109.99
Fanxiang SSD 4TB 2TB 1TB 512GB SATA SSD 2.5'' III Internal Solid State Drive lot
$113.99