Just sell your old Deck and get the new one, Deck display sucks even compared to other LCDs like Rog Ally and Legion Go, the bigger Deck Oled display instead is just perfect, a night and day difference, unlimited contrast, true blacks, perfect colors, sharper image, 90hz, it also supports 1000 nits HDR which is incredible and never seen on any handheld before, it really changes the gaming experience. Also you will get about 40% better battery life, which for an handheld is the most important thing after the display quality(since you play games looking at the display all the time). Performance difference is minimal but even that 5 to 10% increase thanks to faster Ram is welcome, plus it will run way cooler and quieter than the old Deck. You really wanna keep playing your games on that crap washed out LCD screen with just 1.5 hours of battery life and shitty WiFi until Deck 2 releases in 2 or 3 years from now?
Compare to some other needs like water, food and shelter, you don’t need any Steam Deck to live.
But would I still buy an OLED Steam Deck given I already own a LCD Steam Deck and happy about it? If you have the disposable income and like what you are seeing in the new Deck (the various upgrades described in OP), I would go ahead and buy it. Since Valve listened to the community and engineered a product according to these input, they deserve a recognition.
This would hopefully send a message to the various companies in the industry that the money is here for you, but only if you listen and work diligently to deliver a products that consumers want. Monetization, microtransaction and other predatory practice are not.