TheOneWithAReallyLongName on Nostr: Since this is a separate thread with a separate audience, I'll copy my answer over, ...
Since this is a separate thread with a separate audience, I'll copy my answer over, hopefully that's appreciated and not an annoyance.
You can find them on the Internet Archive. At least, I've found up through PSX gen on there. It can help to search for packs from well known release or collection groups. For example, No-Intro is really popular for SNES era and earlier, not sure if they did later gens or not. If you search for No-Intro ROM packs, you'll probably find complete packs for systems, like all or nearly all the SNES games in one bundle, or for later systems with larger games like PSX, something like all games A-F in one bundle, G-L in another, etc.
You can find them on the Internet Archive. At least, I've found up through PSX gen on there. It can help to search for packs from well known release or collection groups. For example, No-Intro is really popular for SNES era and earlier, not sure if they did later gens or not. If you search for No-Intro ROM packs, you'll probably find complete packs for systems, like all or nearly all the SNES games in one bundle, or for later systems with larger games like PSX, something like all games A-F in one bundle, G-L in another, etc.