I am by no means an expert, I haven't long started my investigations in GLP-1s, but I have been an avid experimenter of pharmacological supplmentation for various cognitive and physiological goals for decades, and I am thinking about stacking my Tirz with Sema, so here's what i've learned so far.
Everyone seems to be aware that Tirz has a dual action at GLP-1 and GIP receptor sites, but what's interesting to note is that it's affinity at GLP-1 is about 5 times weaker than Sema. From what I gather the majority of the appetite suppressing effects are from GLP-1 activation, where as GIP is associated with anti-emetic/anti-nausea effects, along with effects that are neuroprotective, increases bone formation, decreases stomach acid secretion, increases insulin release, stimulates fatty acid synthesis, and it's activity at GLP-1 seems to be strong enough to promote the weight loss effect.
My reasoning is, adding Sema to Tirz (Sema low dose, be careful starting off to avoid nausea) should give the stack that boost in appetite suppression that folks like us feel is a little lacking with Tirz only, while also still providing a lot of the benefits that I listed above that tirz provides.
I've seen people recommend stuff like Cagri to stack for suppression, but with grey Sema being so cheap, I don't see any advantages to justify the extra cost personally, although I am still learning.
I've just bought some Sema to add to my Tirz. My dose of Tirz is only 5mg, I plan to keep both drugs as low as possible for as long as possible, when I add in sema, it'll be at 0.25mg and I will titrate up as required for the appetite suppression i'm seeking.