Unfortunately, due to the nature of Beta software, it might appear as "Not certified" and can remain as such for the whole duration of Beta.
Once the official Android 10 is launched, it will not be a problem, but during the Beta you may experience problem with apps that require the software to be certified.
I agree this is deeply irritating and unexpected. I much prefer Google Pay.
HOWEVER - there is a workaround for your bank not supporting Samsung Pay, at least for those of you in the UK, and it has some handy additional benefits.
I have a Curve card, which is a physical card that allows you to add all your Mastercard and Visa cards (not Amex currently), and pay online or in-store (PIN or contactless), and 'map' the payment to whichever card you choose. This means you only need to carry one card, not multiple. The app keeps track of what you spent on what card as well, so you have a unified spending history.
If you forget to swap, for example you pay whilst mapped to your personal card and it should have been on our your company card, you can go "back in time" and swap the transaction to the correct card.
On top of that, it allows you to use credit cards where they wouldn't normally be allowed e.g. Costco, because the Curve card shows as a debit card aaaaaaaaaand (in the UK), you can add your Curve card to both Google Pay AND Samsung Pay 😄
Hey presto - suddenly your bank 'does' support Samsung Pay. (Actually, it's allowed me to also use my Tesco Mastercard on Google Pay - bonus!)
Plus (yes, there's more), Curve does not charge fees foreign transactions or ATM withdrawals made abroad (subject to T&CS). You can make purchases in foreign currency converted at the real exchange rate i.e. the rate at which banks exchange money, also known as the interbank rate or mid-market rate. (There are certain limits on the amount up to which you can make fee-free transactions or ATM withdrawals, after which charges will apply).
The basic/blue Curve card is absolutely free. I've been using mine for about 9 months now and I absolutely love it - wouldn't be without it.
If this sounds like something useful to you, use this link to sign up and you'll get £5 when you make your first transaction with your Curve card.
I have no affiliation with Curve other than being a very happy customer - hope this helps a few people 😄