Is it okay to take moderna after two sinopharm shots?

I dont know what you mean by OK. In general recommendation is to stick with the same one as this combo has not been studied. And you will be doing your own experiment, Tell us how you do if you go that way.

Those 2 vaccines work as different mechanisms. For sure, sinopharm vaccine is less effective compared with moderna by literature. If you decide to use moderna for better protection, you can take moderna but you will need booster shot after the first month and then 6-8 months later. There is no contraindication to use both of them and you cannot enter US or European countries with sinopharm proof.