ETH transaction pending - why is gas so complicated?!

Flagged this as discussion as I'm not exactly looking for advice, but I'm sure I'll get some anyway. More just a comment on how wallets work and gas fees. I understand how gas fluctuates and so on, but surely it doesn't have to be this fiddly?

So, I have some Lido tokens that I wanted to move from one of my Trezor accounts to an exchange. I had forgotten to leave any ETH in that account for gas. No worries, I'll just send a little from the exchange, fees are super low, I checked a tracker, it said 2 gwei average, although I'm not exactly sure how that translates to dollars for a transfer. Anyway, I take a guess and send $5 worth, no problem.

Then I do the transaction to send the Lido. It tells me the gas is less than $1. I've never seen it that low, but I've also never seen fees at 2 gwei so I assume it's accurate. Create and sign the transaction, done. Then I decide to send the remaining Eth to a separate account on my Trezor as there's nothing left on this one but scam tokens. So I create that transaction, fees are also just cents.

Now when I go back to it, I see that both transactions are still pending, presumably because they don't have enough gas. I can't even bump them with more gas because the remaining ETH is tied up in that second transaction. So, what? Now I have to send even more from the exchange to bump these two transactions?! And then I'll probably end up with more dust there that I can't move?

I don't understand why Trezor quoted such low fees if it wasn't going to go though? I get that fees fluctuate but fine, just overestimate it a little or something. I know that I could have set it manually but again, why do they make it so complicated?

I don't need the funds moved urgently but it's been 15 hours so far, do you think it'll go through eventually or I'm going to have to fiddle around even more to push it through?