@strongbow While I do agree that it's much more straight-forward to replace the entire display, a quick look at prices tells me that you can get the front glass for around $25 USD, while even the LCD Incell versions of the screen assembly are running at least twice that, more than $50. If you want an actual soft OLED replacement, then you're looking at closer to $100 to $200.
My brother and I experimented on an old iPhone 5C with replacing the front glass one time without special equipment. It was a pain and took a while to get the old OCA cleaned off, but in the end the result was, shall we say, acceptable. There were small bubbles apparent within the display, but all in all it was usable and not overtly awful.
So all in all, I'd say if you don't mind the amount of work and are willing to put up with a less than perfect result, go for it. You can always spring the big bucks for a full replacement later if it doesn't come out.
To answer your actual question, @millemose, I don't know about mixing those adhesives. My gut impression says it's probably not a good idea, but I see why you'd want to do it.
On the other hand, I did come across at least one vendor selling the screen with the liquid OCA included in a bottle, which seems to be what you were looking for in the first place. Depending on where you're located, this may or may not work for you, but if there's one there's probably more available.
Front Screen Glass Replacement - Compatible with iPhone 12 Pro Max Series 6.7 inch,Tempered Glass Replacement Kit with Repair Tools,Waterproof Adhesive(NO OLED & Touch Digitizer) - Walmart.com