I'm really proud of my solution to part 2. When I first read it, I was freaking stumped, I had no idea how to approach it. I was wondering if I was going to wind up resorting to brute forcing it in factorial time. But then I had an idea on the way home, and I one shotted it! (Got a few tests on the example but first try on the actual input)

from day3_p1 import get_input, get_banks, sample

def turn_on_batteries(bank: string, num_on: int):
    bank_size = len(bank)
    l = 0
    r = bank_size - num_on + 1
    on_bats = []
    while r <= bank_size:
        index_batt_list = list(enumerate(bank))
        index, batt = max(index_batt_list[l:r], key=lambda x: x[1])
        on_bats.append(batt)
        old_l = l
        l = index + 1
        r += 1
    return int("".join(on_bats))


actual = get_input("input")

if __name__ == "__main__":
    all_banks = get_banks(actual, "\n")
    res = 0
    for bank in all_banks:
        res += turn_on_batteries(bank, 12)
    print(res)

Part 1 for completeness:

def get_input(path: str) -> str:
    with open("input") as f:
        data = f.read()
    return data.strip()

def get_banks(data: str, sep=" ") -> list[str]:
    return data.split(sep)

def find_max_battery(bank: str, heap_size=2) -> int:
    batteries = list(enumerate([int(c) for c in bank]))
    first_digit = max(batteries, key=lambda x: x[1])
    if first_digit[0] == len(bank) - 1:
        first_digit = max(batteries[:-1], key=lambda x: x[1])
    second_digit = max(batteries[first_digit[0]+1:], key=lambda x: x[1])
    return first_digit[1] * 10 + second_digit[1]



sample = "987654321111111 811111111111119 234234234234278 818181911112111" 
actual = get_input("input")

DATA = actual
if __name__ == "__main__":
    all_banks = get_banks(DATA, "\n")
    res = 0
    for bank in all_banks:
        res += find_max_battery(bank)
    print(res)