With both Trezor and Ledger it is possible to use Electrum as the GUI (interface) app. So if they go out of business and/or stop supporting the specific hardware wallet model that you own, you can continue using it with Electrum. Alternatively, you can import the seed backup (12 or 24 words) into a new hardware wallet.

The users weren't unable to access their funds. However, Ledger Live (their desktop and mobile app) uses nodes hosted by Ledger, so effectively this meant that non-technical users who relied on their hosted nodes couldn't access their funds.

One could (and should!) still use the same wallet with a self-hosted node, or a third-party one, by using the wallet with a different software (which is also officially supported; Ledger provides docs for doing so).