Cashing USD $ checks

You need to check with your local bank. Likely a local VN bank cant/wont... Maybe Citibank or HSBC or another can.
I know US banks will in the US, it takes a long time on hold, but VN is totally different.

contact some banks including yours in VN.

Agreed, my Nam A Bank in Can Tho has indicated they can not do

I'll reply tomorrow with everything you need to know. You ain't going to like it though. BEER TIME.
Rick

Funny how Benjamins ($100 bills for you Euro people) are practically the "coin of the realm" in Vietnam but you can't cash a $100 check.

Well unfortunately having gone through this a few times in the past 15 years here, my suggestion is this. If it's a check drawn on a USA bank, have the sender cancel it and send the money with TRANSFERWISE or MONEYGRAM to you. If it's a US Government  Treasury check you'll need to open account with ANZ (if their still operating in VN) or HSBC then deposit the check with them in your account. It'll take about 3 weeks to clear and your looking at a transaction fee for about 3% up to 6%. The other option is to sign it over to a 3rd party that you trust back in the States, mail it to them to cash it for you and send it back through the two above (TW or MG) to you. Forget about any Local VN banks, and don't waste your time asking, it ain't going to happen. If you do decide to mail it back to the States on the VN Customs form claim it as a "Financial Document" not a money check.
Rick

Feedback appreciated and understand local issues processing check-working through options with issuer in US

Agreed with everyone above. There are no local VN banks that will cash a check drawn on US dollars. Like almost everyone, I've tried it and it just isn't happening.
Next time you're back in America I strongly suggest you open an account there - preferably with HSBC, Citibank  or one of those known to be more expat friendly.

Have git options in US with my account, but 3rd party required.

Appreciated feedback