Hi! What do you mean by “spare parts”? There are tons of spare parts and upgrades on the MNT Shop.
If you’re looking for individual components, like the charge port, please refer to the long list of components that is publicly available here. This is the whole BoM and includes every single component.
To answer your questions about charging: the MNT Reform uses this barrel jack for DC input, labelled as J1 on the motherboard.
There is a USB-C charging variant of the motherboard created by @jacqueline but I’m unsure she has made the design files public anywhere. Other users, myself included, have been able to charge with a high enough wattage USB-C brick and the type of USB-C PD to DC barrel cable discussed in this thread here.