No specific time frame, just that month or few weeks around Black Friday and leading up to Christmas, everything short of January 1st sales. 

PS5 has passed Switch 2 already. Will Switch 2 get a big boost like launch around the US Holidays which I guess we now take part in globally...

I would be very surprised if Switch 2 didn't take it but there is an actual chance that PS5 might or at least be close... hell with people getting ready for GTA6...maybe PS5. Hummmp. Maybe

In Europe the PS5 should sell more, In the US the Switch should sell more

Depends on Switch 2 stock, and how good PS5 & NSW deals are. That said… I’m not sure. Probably Switch 2? I’d imagine it’ll be close as Nintendo often sells most during December, whereas PlayStation traditionally has an equally big November to December.

Normally I'd say the new console doesn't have a chance because of stock.

But switch 2 stock is plentiful, not seen that for a new system in a long time. Mine was delivered launch day, I wouldn't have expected they'd just be available on Amazon whenever you want one so soon.

In terms of global sales it could go either way.

Small to moderate win for Switch 2 in the USA. There will be a small to moderate win for PS5 in Europe. Japan will obviously be a landslide for Switch 2. In some other areas like China, Oceania, South America, the Middle East, Africa and so on it could probably go either way.
Globally? Probably a small win for Switch 2 but it could go either way.
Switch 2 has plentiful stock, is a hot new item and has a growing library of Nintendo games. It also helps that in the USA Switch 2 is $50 cheaper than the Digital Edition of PS5 and $100 cheaper than PS5 with an optical drive.
In the likely event Nintendo raises Switch 2 hardware prices, expect it to happen as early as January but maybe as late as April or May so that they get through their fiscal year first.

PS5 will have better deals so it will be close. I'd say small win for Switch 2 worldwide

Switch 2 should win as it will likely lead in North America and Japan, provided there is sufficient stock.

Could be close though if PS5 has aggressive deals and Nintendo doesn't, though a system in its prime selling better than one that's newer isn't unusual, PS4 outsold Switch 1 at various points in 2017-2018.

PS5 will because Sony will give significant price cuts; especially outside the USA. Who is voting for the Switch 2? Lol. Although, I guess I can be wrong.

Though Switch 2 isn't following the same sales pattern as most launches, because unlike most recent devices its stock has been plentiful. So it's sales haven't been limited and it's been through the roof. Normally a launch year console wouldn't stand a chance but things are very different in the Switch 2's case. That it's sold over 8m in it's first 3 months and I can still go to amazon and get one delivered tomorrow is unheard of in recent times.

It also likely means it's growth YoY is likely to be less in the future. As in, the Switch 1's peak year was well over double it's launch year sales. I don't see Switch 2's peak matching that proportional growth because Switch 2's first year is so strong. So Switch 2 as a new console isn't going to be as far from it's prime as launch systems typically are.

So I'm unsure of Switch 2 vs PS5 this holiday. Because indications are that Nintendo are keeping up with demand just fine so it should be big. But also PS5 has had very strong holiday performances recently, compared to the PS4 it's generally done worse in the earlier parts of the year but better in the holidays. So if the PS5 has good promotions it can sell a lot of units. Though Nintendo also usually gets a bigger December boost than other consoles. Could easily be BF win for PS5 but an overall holiday season win for Switch 2.

I'm still undecided in this battle. 

I don't think they will but if they do and with GTA6 around the corner I think PS5 will win. As of now, if all things are equal and they have the same stock then it's hard to say which will win.