People using metadone in conjunction with a GABA-centric Receptor Modulating substance like Benzos or Pregabalin swear by it. Methadone cannot produce euphoria per se, but when combined with the aforementioned substances, off to the races. There is a huge & very dangerois "blackout" (i.e. Amnesiac interval. Again, forget about euphoria, sedation though is very heavy. A large number of folks primarily seek sedation.
Methadone absolutely can produce euphoria.
Unless you're just referring to people who are tolerant to it & on it already, then yeah. Most opioids use their euphoria after awhile.
I feel like benzos & such aren't the greatest mix with opioids IMO. It's not going to bring about the same opioid euphoria, it's just adding another drugs effects ontop of the opioid. And since benzos can actually decrease neurotransmitter release, you can actually prevent or kill euphoria from drugs with a benzo.
Benzos can cause euphoria for some people though on their own, but it's usually because if you have anxiety & take something, you might feel a little euphoric from the relief of your anxiety.
In general though, throwing benzos or pregablin ontop of opioids is going to increase sedation & risk for respiratory depression, all for vague euphoria, that you might not even get every time.
The best way to get euphoria back from methadone would be either opioid rotation or dose reduction for a few days. Way less risky then trying to throw more drugs ontop of it.
I personally have been on opioids for 16+ years now & I don't particularly 'seek sedation" from them. Opioids make me energized, content, blissful, creative, sensual, etc... So that's what I expect from an opioid when I use one. The sedation is generally just a side effect & depending on the opioid, is some times transient or presents itself as this dual stimulated/sedated feeling.
If people are looking for sedation, they could find it in a million other drugs that are way more sedating than opioids. I think people mistakenly believe that sedation makes a drug worthwhile, but that's just not necessarily the case. After all, if it was just 'sedation' that I cared about, I'd go get black out drunk & skip having an opioid problem altogether.