# create nether portal
fill -1 63 -2 2 63 -2 obsidian
fill -1 63 -2 -1 68 -2 obsidian
fill 2 63 -2 2 68 -2 obsidian
fill -1 68 -2 2 68 -2 obsidian

# add flint_and_steel to chest
execute in overworld run item replace block 4 64 0 container.2 with flint_and_steel 1