No Way Home established that Tom Hardy's Venom exists in a separate universe from the MCU, but it is part of the same multiverse. Venom temporarily crossed over to the MCU in the post-credits scene, so there's no reason it couldn't happen again, or that Tom Holland couldn't crossover too. But I can't see Holland's Spidey permanently leaving the MCU as long as the Marvel/Sony deal is still in place, he's too popular.