During the October ice storm when I had no power for a week at the house, I ran my 22" TV from a cheap inverter I carry in my work truck. The inverter has a power meter LED display and it claimed that my TV drew less than 10 watts. I don't watch TV, but when I do, it's OU football. I watched the whole game and never even had to start the truck...the display on the inverter also shows volts, and it never dropped more than a few tenths below twelve volts.
I ran a Bosch hammer drill with that same inverter a few years ago. The drill data plate says 9 amps iirc, and the inverter is claimed to handle 1000W. It ran the drill just fine. Long enough to bore a 1" diameter hole through 14" of concrete at a remote tank with no available power.
In both cases, I raised the hood and clamped the inverter power leads straight to the battery. And running that big drill, I did keep the truck running. I have never gone to the trouble of running 2awg wire through the firewall of my work truck and as rarely as I use that inverter, it really isn't worth the bother.
I don't think modern laptop power supplies are that sensitive to dirty incoming AC. I have a cheap 120w inverter that looks like a coffee mug that seems to do okay running the laptop power supply (just a normal latitude, not a precision!), although it does occasionally fault out (power LED goes from green to red and it beeps at me).
I can run that little one plugged into the cigar lighter. It looks like this one:
https://www.autozone.com/12v-produc...XiJAi5lzoz-Seg5p3qm4DHjaTbWArfWAaAqL0EALw_wcB