Self-jumpstarting means jumpstarting one's own vehicle without the use of another vehicle. The most common way to do this is by combining house and chassis batteries.
It will be gentlest on the system to combine the batteries and allow the starter battery to come up a bit instead of immediately attempting to start.
This will be easiest if one already has some kind of isolator/combiner setup. If not, one can run jumper cables from the house bank, or physically remove the house bank and carry it to the starter battery area.
Switches used as manual isolators will self-jumpstart when in the ON position.
Solenoids/relays always self-jumpstart assuming there is enough voltage in the starter battery to energize the solenoid. It is a mechanical connection and power will flow both ways.
It is common for VSRs to have a button to combine the batteries for self-jumpstarting.
Solid state isolators are diode based and will not allow power to flow from the house battery to the starter battery. Therefore they cannot be used to self-jumpstart.
Some DC-DC chargers with integrated solar charge controllers can keep the starter battery maintained after the house batteries are charged. This would help avoid the “dead starter battery” situation in the first place.
[Note from secessus: AFAIK none of the DC-DC chargers allow self-jumpstarting. If anyone knows otherwise, please point me to the documentation. Thanks!]
Lithium "jump packs" have become more popular. Lithium-chemistry batteries can discharge quickly, so even relative small packs can jumpstart a car.
'Dwellers may want to pick a jump pack that has 12v or USB outlets so it can have other uses.