https://bitcoin.stackexchange.com/questions/9709/do-unconfirmed-transactions-expire#:~:text=Oh%2C%20and%20I%20forgot%20the,but%20that%20is%20really%20unlikely.

Oh, and I forgot the most important part: transactions on Bitcoin (tx frames in the protocol) don't have a 'time' field, which means that transaction expiration can't be a feature of Bitcoin.

To summarize: yes, the transaction can expire, but that is really unlikely.

It looks like you're sort of right.

Someone could troll you by saving an expired operation and rebroadcasting it to the network later.

However, none of those UTXOs would be spendable if they've already been spent.
Again because it's not an account based system the pubkey itself is irrelevant.
Only the UTXO matters in this regard.

Therefore if you consolidated your UTXOs you could use the same pubkey and this would create a new UTXO that was completely unspendable by an expired transaction (because that expired transaction points to a spent TX). Basically if you spend that UTXO it can't be spent again which is why this model is so important in the first place.