QUESTION: If Metamask confirms a contract interaction, but the transaction remains unsuccessful due to network congestion, could the nonce remain neglected indefinitely?

Hi all. Please bear with the length of this post - I'm a noob and I'm trying to make sense of the nuance. Here's the context:

I initiated an ERC-20 token swap through Matcha (via Uniswap, by way of a Metamask wallet) about 3 hours ago - after paying the gas fee, Matcha declared a successful trade and the contract interaction was submitted.

According to Metamask, the smart contract interaction was confirmed...but, because the transaction remains pending, the token exchange has yet to occur.

Between the time I initiated the transaction and the nonce made its way into the queue, the network became very congested. The gas fee I paid was about 1/3rd of what it would have been, should the transaction have been initiated a short time later.

This is what leads into my question - If a contract interaction is confirmed, but the transaction remains unsuccessful due to network congestion, could the nonce remain neglected indefinitely?

In other words - If it is impossible to pay the gas "speed up" fee, thus incentivising solving of the nonce, is the successful completion of the transaction (and the duration thereof) at risk of falling into oblivion?

At the very least, I assume transaction confirmation will (at the earliest) occur once the level of network traffic declines to where it was pre-initiation...but could it, theoretically, remain unconfirmed for days if sustained congestion levels declares it a low priority?